import java.util.*;

class Main{
	static Scanner s=new Scanner(System.in);
	static int gInt(){
		return Integer.parseInt(s.next());
	}
	public static void main(String[] A){
		int a=gInt();
		long r=1;
		for(int i=2;i<a;++i){
			long v=i*i;
			if(v<=a){
				while(v*i<=a)
					v*=i;
				r=Math.max(r,v);
			}
		}
		System.out.println(r);
	}
}

/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