import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        TreeSet<Integer> set = new TreeSet<>();
        set.add(1);
        for(int i = 2 ; i <= Math.sqrt(n) ; i++){
            for(int j = i*i ; j <= n; j*=i){
                set.add(j);
            }
        }
        System.out.println(set.last());

    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz