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 main(){
int X;
cin >>X;
vector <bool > expo(X+1);
expo[1]=1;
for(int b=2;b<=X;b++){
int v = b*b;
while(v<=X){
expo[v] = 1;
v *= b;
}
}
for(int i=X;i>=1;i--) if(expo[i]){
cout <<i<<endl;
return 0;
}
}