import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    }

} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    } main {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int X = sc.nextInt(); X sc.nextInt() sc.nextInt sc sc.close() sc.close sc int ans = 1; ans 1 for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        } int i = 2; int i = 2; i 2 i < 32 i 32 i++ i++ i {
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        } {
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        } int tmp = 1; tmp 1 tmp *= i tmp i while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            } tmp <= X tmp X {
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            } tmp *= i tmp i if(tmp <= X) ans = Math.max(ans, tmp);
                else break; tmp <= X tmp X ans = Math.max(ans, tmp) ans Math.max(ans, tmp) Math.max Math ans tmp break; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();
        int ans = 1;
        for(int i = 2; i < 32; i++){
            int tmp = 1;
            tmp *= i;
            while(tmp <= X){
                tmp *= i;
                if(tmp <= X) ans = Math.max(ans, tmp);
                else break;
            }
        }
        System.out.println(ans);

    }

}
