import java.util.Scanner;
public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scan=new Scanner(System.in);
		int a=scan.nextInt();
		int ans=1;
		for(int i=0;i!=a+1;i++) {
			for(int j=2;j<=Math.sqrt(i);j++) {
				for(int k=j;k<=i;k*=j) {
					if(k==i) {
						ans=i;
					}
				}
			}
		}
		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