Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

10

Sample Output 1

9

There are four perfect powers that are at most 10: 1, 4, 8 and 9.
We should print the largest among them, 9.

Sample Input 2

1

Sample Output 2

1

Sample Input 3

999

Sample Output 3

961

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

int main(){
  int X;
  cin >> X;
 if(X>=1 && X<=3){ 
   cout << 1 << endl;
 }
  else{
  int b = 2;
  int ans = 0;
  while(b<=40){
  int Y = 1;
  while(true){
   Y = Y*b; 
  if(Y > X) break;
  
  ans = max(Y,ans); 
  }
  b++;
  }
   cout << ans << endl;
  }
}