import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;


public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    }

    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());
        }

    }
} 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.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    }

    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());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, 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) TaskA solver = new TaskA(); solver new TaskA() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    } TaskA public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        } log {
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        } int num= 0; num 0 while (a>=b){
                a/=b;
                num++;
            } a>=b a b {
                a/=b;
                num++;
            } a/=b a b num++ num return num; num int a a int b b public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        } solve {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        } int x = in.nextInt(); x in.nextInt() in.nextInt in int max= 1; max 1 for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                } int i = 2 ; int i = 2 ; i 2 i < x i x i++ i++ i {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                } {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                } int v = log(x , i); v log(x , i) log x i int ans = (int) Math.pow(i,v); ans (int) Math.pow(i,v) Math.pow Math i v if ( v > 1 && max <= ans) max = ans; v > 1 && max <= ans v > 1 v 1 max <= ans max ans max = ans max ans out.print(max) out.print out max int testNumber testNumber 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());
        }

    } 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 class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    }

    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 class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    }

    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());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;


public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA {
        public static int log(int a , int b){
            int num= 0;
            while (a>=b){
                a/=b;
                num++;
            }
            return num;
        }
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int x = in.nextInt();
                int max= 1;
                for (int i = 2 ; i < x; i++) {
                    int v = log(x , i);
                    int ans = (int) Math.pow(i,v);
                    if ( v > 1 && max <= ans) max = ans;
                }
                out.print(max);
        }

    }

    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());
        }

    }
}
