import java.io.*;
import java.lang.*;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
import java.math.BigInteger;

public class Main {
    //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    }

    static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    }

    static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    }
} import java.io.*; io.* java import java.lang.*; lang.* java import java.io.InputStream; InputStream java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.BufferedReader; BufferedReader java.io import java.io.OutputStream; OutputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.io.IOException; IOException java.io import java.util.Arrays; Arrays java.util import java.util.Random; Random java.util import java.util.StringTokenizer; StringTokenizer java.util import java.math.BigInteger; BigInteger java.math public class Main {
    //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    }

    static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    }

    static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    }
} Main //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.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 out = new PrintWriter(outputStream); out new PrintWriter(outputStream) Task solver = new Task(); solver new Task() int t = 1; t 1 for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out); int tt = 1; int tt = 1; tt 1 tt <= t tt t tt++ tt++ tt solver.solve(tt, in, out); solver.solve(tt, in, out) solver.solve solver tt in out out.close() out.close out String[] args args static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    } sort {
        shuffle(x);
        Arrays.sort(x);
    } shuffle(x) shuffle x Arrays.sort(x) Arrays.sort Arrays x int[] x x static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    } sort {
        shuffle(x);
        Arrays.sort(x);
    } shuffle(x) shuffle x Arrays.sort(x) Arrays.sort Arrays x long[] x x static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    } shuffle {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    } Random get = new Random(); get new Random() for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } int r = get.nextInt(a.length); r get.nextInt(a.length) get.nextInt get a.length a a.length int temp = a[i]; temp a[i] a i a[i] = a[r] a[i] a i a[r] a r a[r] = temp a[r] a r temp int[] a a static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    } shuffle {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    } Random get = new Random(); get new Random() for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        } int r = get.nextInt(a.length); r get.nextInt(a.length) get.nextInt get a.length a a.length long temp = a[i]; temp a[i] a i a[i] = a[r] a[i] a i a[r] a r a[r] = temp a[r] a r temp long[] a a static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    } Task public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        } solve {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        } String s = in.next(); s in.next() in.next in char[] c = s.toCharArray(); c s.toCharArray() s.toCharArray s int len = 0; len 0 int max = 0; max 0 for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            } int i = 0; int i = 0; i 0 i<3 i 3 i++ i++ i {
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            } {
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            } if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                } c[i]=='R' c[i] c i 'R' {
                    ++len;
                } ++len len {
                    max = Math.max(max,len);
                    len = 0;
                } max = Math.max(max,len) max Math.max(max,len) Math.max Math max len len = 0 len 0 out.println(Math.max(max,len)) out.println out Math.max(max,len) Math.max Math max len int tt tt InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public long nextLong() {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public double nextDouble() {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        } nextLine {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        } try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            } Exception e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                return reader.readLine();
            } return reader.readLine(); reader.readLine() reader.readLine reader return null; null public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        } hasNext {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        } String next = null; next null try {
                next = reader.readLine();
            } catch (Exception e) {
            } catch (Exception e) {
            } Exception e {
            } {
                next = reader.readLine();
            } next = reader.readLine() next reader.readLine() reader.readLine reader if (next == null) {
                return false;
            } next == null next null {
                return false;
            } return false; false tokenizer = new StringTokenizer(next) tokenizer new StringTokenizer(next) return true; true public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        } nextInta {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        } int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++) a[i] = nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextInt(); a[i] = nextInt() a[i] a i nextInt() nextInt return a; a int n n public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        } nextLonga {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        } long[] a = new long[n]; a new long[n] n for (int i = 0; i < n; i++) a[i] = nextLong(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextLong(); a[i] = nextLong() a[i] a i nextLong() nextLong return a; a int n n public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        } nextIntm {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        } int[][] a = new int[n][m]; a new int[n][m] n m for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            } {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            } for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                } int j = 0; int j = 0; j 0 j < m j m j++ j++ j {
                    a[i][j] = nextInt();
                } {
                    a[i][j] = nextInt();
                } a[i][j] = nextInt() a[i][j] a[i] a i j nextInt() nextInt return a; a int n n int m m public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        } nextLongm {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        } long[][] a = new long[n][m]; a new long[n][m] n m for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            } {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            } for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                } int j = 0; int j = 0; j 0 j < m j m j++ j++ j {
                    a[i][j] = nextLong();
                } {
                    a[i][j] = nextLong();
                } a[i][j] = nextLong() a[i][j] a[i] a i j nextLong() nextLong return a; a int n n int m m public BigInteger nextBigInteger() {
            return new BigInteger(next());
        } nextBigInteger {
            return new BigInteger(next());
        } return new BigInteger(next()); new BigInteger(next()) public class Main {
    //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    }

    static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    }

    static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    }
} public class Main {
    //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    }

    static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    }

    static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    }
} Main
import java.io.*;
import java.lang.*;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
import java.math.BigInteger;

public class Main {
    //code written by a living bruh moment
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        int t = 1;
        for (int tt = 1; tt <= t; tt++) solver.solve(tt, in, out);
        out.close();
    }

    static class Task {

        public void solve(int tt, InputReader in, PrintWriter out) {
            String s = in.next();
            char[] c = s.toCharArray();
            int len = 0;
            int max = 0;
            for(int i = 0; i<3; i++){
                if(c[i]=='R'){
                    ++len;
                }
                else{
                    max = Math.max(max,len);
                    len = 0;
                }
            }
            out.println(Math.max(max,len));
        }
    }

    static void sort(int[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void sort(long[] x) {
        shuffle(x);
        Arrays.sort(x);
    }

    static void shuffle(int[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            int temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static void shuffle(long[] a) {
        Random get = new Random();
        for (int i = 0; i < a.length; i++) {
            int r = get.nextInt(a.length);
            long temp = a[i];
            a[i] = a[r];
            a[r] = temp;
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            try {
                return reader.readLine();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public boolean hasNext() {
            String next = null;
            try {
                next = reader.readLine();
            } catch (Exception e) {
            }
            if (next == null) {
                return false;
            }
            tokenizer = new StringTokenizer(next);
            return true;
        }

        public int[] nextInta(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        public long[] nextLonga(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }

        public int[][] nextIntm(int n, int m) {
            int[][] a = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextInt();
                }
            }
            return a;
        }

        public long[][] nextLongm(int n, int m) {
            long[][] a = new long[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    a[i][j] = nextLong();
                }
            }
            return a;
        }

        public BigInteger nextBigInteger() {
            return new BigInteger(next());
        }
    }
}