import java.util.Scanner;

public class Main {

    public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    }
} Main public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    } main {
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int x = scanner.nextInt(); x scanner.nextInt() scanner.nextInt scanner double ans = 1; ans 1 for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       } int i = 2; int i = 2; i 2 i < x i x i++ i++ i {
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       } {
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       } for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           } int j = 2; int j = 2; j 2 Math.pow(i,j) <= x Math.pow(i,j) Math.pow Math i j x j++ j++ j {
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           } {
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           } if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               } ans < Math.pow(i,j) ans Math.pow(i,j) Math.pow Math i j {
                   ans = Math.pow(i,j);
               } ans = Math.pow(i,j) ans Math.pow(i,j) Math.pow Math i j System.out.println((int)ans) System.out.println System.out System System.out (int)ans String args[] args public class Main {

    public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    }
} public class Main {

    public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    }
} Main
import java.util.Scanner;

public class Main {

    public static  void main(String args[]){
        Scanner scanner = new Scanner(System.in);
       int x = scanner.nextInt();
       double ans = 1;
       for (int i = 2; i < x; i++){
           for(int j = 2; Math.pow(i,j) <= x; j++){
               if(ans < Math.pow(i,j)){
                   ans = Math.pow(i,j);
               }
           }
       }
       System.out.println((int)ans);
    }
}
