You are given a positive integer X. Find the largest perfect power that is at most X. Here, a perfect power is an integer that can be represented as b^p, where b is an integer not less than 1 and p is an integer not less than 2.

Constraints

* 1 ≤ X ≤ 1000
* X is an integer.

Input

Input is given from Standard Input in the following format:


X


Output

Print the largest perfect power that is at most X.

Examples

Input

10


Output

9


Input

1


Output

1


Input

999


Output

961
    #include <bits/stdc++.h>
    using namespace std;
     
    int N,maxn=1;
     
    int main(){
    	cin>>N;
    	for(int i=2;i<=10000;i++){
    		int f=i*i;
    		while(f<=N){maxn=max(maxn,f);f*=i;}
    	}
    	cout<<maxn<<endl;
    	return 0;
    }