import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
import java.util.InputMismatchException;


/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Manan Patel
 */
public class Main{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    }

    static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    }
    static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

} import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.*; util.* java import java.util.InputMismatchException; InputMismatchException java.util public class Main{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    }

    static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    }
    static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter w = new PrintWriter(outputStream); w new PrintWriter(outputStream) Solution solver = new Solution(); solver new Solution() solver.solve(1 , in, w) solver.solve solver 1 in w w.close() w.close w String[] args args static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    } Solution public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        } solve {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        } if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a"); Character.isUpperCase(sc.next().charAt(0)) Character.isUpperCase Character sc.next().charAt(0) sc.next().charAt sc.next() sc.next sc 0 w.println("A") w.println w "A" w.println("a") w.println w "a" int tc tc InputReader sc sc PrintWriter w w static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    } f public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        } max {
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        } long ans = Long.MIN_VALUE; ans Long.MIN_VALUE Long Long.MIN_VALUE for (long i : a)
                ans = Math.max(ans , i); long i a ans = Math.max(ans , i); ans = Math.max(ans , i) ans Math.max(ans , i) Math.max Math ans i return ans; ans long a[] a public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        } power {
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        } long res = 1; res 1 while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            } y > 0 y 0 {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            } if ((y & 1) == 1)
                    res = (res*x); (y & 1) == 1 (y & 1) y 1 1 res = (res*x) res (res*x) res x y = y >> 1 y y >> 1 y 1 x = x * x x x * x x x return res; res long x x int y y public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        } powerm {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        } long res = 1; res 1 x %= p x p while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            } y > 0 y 0 {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            } if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                } (y & 1) == 1 (y & 1) y 1 1 {
                    res *= x;
                    res %= p;
                } res *= x res x res %= p res p y >>= 1 y 1 x *= x x x x %= p x p return res; res long x x long y y long p p public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        } sort {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        } int n = arr.length n arr.length arr arr.length mid mid h h s s l l i i j j k; k int[] res = new int[n]; res new int[n] n for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            } s = 1; s = 1 s 1 s < n s n s <<= 1 s <<= 1 s 1 {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            } {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            } for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                } l = 0; l = 0 l 0 l < n - 1 l n - 1 n 1 l += (s << 1) l += (s << 1) l (s << 1) s 1 {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                } {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                } h = Math.min(l + (s << 1) - 1, n - 1) h Math.min(l + (s << 1) - 1, n - 1) Math.min Math l + (s << 1) - 1 l + (s << 1) l (s << 1) s 1 1 n - 1 n 1 mid = Math.min(l + s - 1, n - 1) mid Math.min(l + s - 1, n - 1) Math.min Math l + s - 1 l + s l s 1 n - 1 n 1 i = l i l j = mid + 1 j mid + 1 mid 1 k = l k l while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]); i <= mid && j <= h i <= mid i mid j <= h j h res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]) res[k++] res k++ k (arr[i] <= arr[j] ? arr[i++] : arr[j++]) arr[i] <= arr[j] arr[i] arr i arr[j] arr j arr[i++] arr i++ i arr[j++] arr j++ j while (i <= mid)
                        res[k++] = arr[i++]; i <= mid i mid res[k++] = arr[i++] res[k++] res k++ k arr[i++] arr i++ i while (j <= h)
                        res[k++] = arr[j++]; j <= h j h res[k++] = arr[j++] res[k++] res k++ k arr[j++] arr j++ j for (k = l; k <= h; k++)
                        arr[k] = res[k]; k = l; k = l k l k <= h k h k++ k++ k arr[k] = res[k]; arr[k] = res[k] arr[k] arr k res[k] res k int[] arr arr public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        } gcd {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        } if (a == 0)
                return b; a == 0 a 0 return b; b return gcd(b % a, a); gcd(b % a, a) gcd b % a b a a long a a long b b public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        } findGCD {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        } long result = arr[0]; result arr[0] arr 0 for (int i = 1; i < n; i++)
                result = gcd(arr[i], result); int i = 1; int i = 1; i 1 i < n i n i++ i++ i result = gcd(arr[i], result); result = gcd(arr[i], result) result gcd(arr[i], result) gcd arr[i] arr i result return result; result long arr[] arr int n n static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    } InputReader private InputStream stream; stream private byte[] buf = new byte[1024]; buf new byte[1024] 1024 private int curChar; curChar private int numChars; numChars private InputReader.SpaceCharFilter filter; filter public InputReader(InputStream stream) {
            this.stream = stream;
        } InputReader {
            this.stream = stream;
        } this.stream = stream this.stream this this.stream stream InputStream stream stream public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        } read {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        } if (numChars == -1)
                throw new InputMismatchException(); numChars == -1 numChars -1 1 throw new InputMismatchException(); new InputMismatchException() if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            } curChar >= numChars curChar numChars {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            } curChar = 0 curChar 0 try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                } catch (IOException e) {
                    throw new InputMismatchException();
                } IOException e {
                    throw new InputMismatchException();
                } throw new InputMismatchException(); new InputMismatchException() {
                    numChars = stream.read(buf);
                } numChars = stream.read(buf) numChars stream.read(buf) stream.read stream buf if (numChars <= 0)
                    return -1; numChars <= 0 numChars 0 return -1; -1 1 return buf[curChar++]; buf[curChar++] buf curChar++ curChar public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        } nextInt {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        } int c = read(); c read() read while (isSpaceChar(c))
                c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read int sgn = 1; sgn 1 if (c == '-') {
                sgn = -1;
                c = read();
            } c == '-' c '-' {
                sgn = -1;
                c = read();
            } sgn = -1 sgn -1 1 c = read() c read() read int res = 0; res 0 do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } if (c < '0' || c > '9')
                    throw new InputMismatchException(); c < '0' || c > '9' c < '0' c '0' c > '9' c '9' throw new InputMismatchException(); new InputMismatchException() res *= 10 res 10 res += c - '0' res c - '0' c '0' c = read() c read() read return res * sgn; res * sgn res sgn public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        } nextLong {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        } int c = read(); c read() read while (isSpaceChar(c))
                c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read int sgn = 1; sgn 1 if (c == '-') {
                sgn = -1;
                c = read();
            } c == '-' c '-' {
                sgn = -1;
                c = read();
            } sgn = -1 sgn -1 1 c = read() c read() read long res = 0; res 0 do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            } if (c < '0' || c > '9')
                    throw new InputMismatchException(); c < '0' || c > '9' c < '0' c '0' c > '9' c '9' throw new InputMismatchException(); new InputMismatchException() res *= 10 res 10 res += c - '0' res c - '0' c '0' c = read() c read() read return res * sgn; res * sgn res sgn public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        } readString {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        } int c = read(); c read() read while (isSpaceChar(c))
                c = read(); isSpaceChar(c) isSpaceChar c c = read() c read() read StringBuilder res = new StringBuilder(); res new StringBuilder() do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c)); !isSpaceChar(c) isSpaceChar(c) isSpaceChar c {
                res.appendCodePoint(c);
                c = read();
            } res.appendCodePoint(c) res.appendCodePoint res c c = read() c read() read return res.toString(); res.toString() res.toString res public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        } isSpaceChar {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        } if (filter != null)
                return filter.isSpaceChar(c); filter != null filter null return filter.isSpaceChar(c); filter.isSpaceChar(c) filter.isSpaceChar filter c return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1 c == '\t' c == '\r' c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1 c == ' ' c ' ' c == '\n' c '\n' c == '\r' c '\r' c == '\t' c '\t' c == -1 c -1 1 int c c public String next() {
            return readString();
        } next {
            return readString();
        } return readString(); readString() readString public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        } SpaceCharFilter public boolean isSpaceChar(int ch); isSpaceChar int ch ch public class Main{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    }

    static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    }
    static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

} public class Main{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    }

    static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    }
    static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
import java.util.InputMismatchException;


/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Manan Patel
 */
public class Main{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter w = new PrintWriter(outputStream);
        Solution solver = new Solution();
        //int testCount = Integer.parseInt(in.next());
        //for (int i = 1; i <= testCount; i++)
            solver.solve(1 , in, w);
        w.close();
    }

    static class Solution {
        public void solve(int tc, InputReader sc, PrintWriter w) {
            if (Character.isUpperCase(sc.next().charAt(0)))
                w.println("A");
            else
                w.println("a");
        }
    }
    static class f{
        public static long max(long a[]){
            long ans = Long.MIN_VALUE;
            for (long i : a)
                ans = Math.max(ans , i);
            return ans;
        }
        public static long power(long x, int y){
            long res = 1;
            while (y > 0)
            {
                if ((y & 1) == 1)
                    res = (res*x);
                y = y >> 1;
                x = x * x;
            }
            return res;
        }
        public static long powerm(long x, long y, long p) {
            long res = 1;
            x %= p;
            while (y > 0) {
                if ((y & 1) == 1) {
                    res *= x;
                    res %= p;
                }
                y >>= 1;
                x *= x;
                x %= p;
            }
            return res;
        }
        public static void sort(int[] arr) {
            int n = arr.length, mid, h, s, l, i, j, k;
            int[] res = new int[n];
            for (s = 1; s < n; s <<= 1) {
                for (l = 0; l < n - 1; l += (s << 1)) {
                    h = Math.min(l + (s << 1) - 1, n - 1);
                    mid = Math.min(l + s - 1, n - 1);
                    i = l;
                    j = mid + 1;
                    k = l;
                    while (i <= mid && j <= h)
                        res[k++] = (arr[i] <= arr[j] ? arr[i++] : arr[j++]);
                    while (i <= mid)
                        res[k++] = arr[i++];
                    while (j <= h)
                        res[k++] = arr[j++];
                    for (k = l; k <= h; k++)
                        arr[k] = res[k];
                }
            }
        }
        public static long gcd(long a, long b)
        {
            if (a == 0)
                return b;
            return gcd(b % a, a);
        }

        public static long findGCD(long arr[], int n)
        {
            long result = arr[0];
            for (int i = 1; i < n; i++)
                result = gcd(arr[i], result);
            return result;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

}
