
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		
		int ans = 1;
		
		for (int i = 2; i * i <= n; i++) {
			for (int j = i * i; j <= n; j *= i) {
				ans = Math.max(ans, j);
			}
		}
		
		System.out.println(ans);
		
	}
	
}
/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