import java.util.*;
public class Main{

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    }
}



 import java.util.*; util.* java public class Main{

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    } main {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc int cnt = 1; cnt 1 int num =0; num 0 int max=0; max 0 for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        } int i =1; int i =1; i 1 i<40 i 40 i++ i++ i {
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        } {
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        } for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            } int j =2; int j =2; j 2 j<40 j 40 j++ j++ j {

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            } {

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            } num = (int)Math.pow(i,j) num (int)Math.pow(i,j) Math.pow Math i j if(max<num && num<=x){
                    max=num;
                } max<num && num<=x max<num max num num<=x num x {
                    max=num;
                } max=num max num System.out.println(max) System.out.println System.out System System.out max String[] args args public class Main{

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    }
} public class Main{

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

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

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int cnt = 1; 
        int num =0;
        int max=0;
        
        for(int i =1;i<40;i++){
            for(int j =2;j<40;j++){

                num = (int)Math.pow(i,j);
                if(max<num && num<=x){
                    max=num;
                }
            }
        }
        System.out.println(max);

    }
}




