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<iostream>
#include<cmath>

using namespace std;

int main(){
  //int y = 2;
  int x;
  cin >> x;
  double b = 0, B = 0;

  for(int i = 0; i < 40; i++){
    for(int j = 0; j < 11; j++){
      b = pow(i,j);
      if( b < x){
        if(b > 0) cout << "b "<<i <<" "<<j<<" :"<<b<<endl;
        if( B < b) B = b;
      }
    }
  }
  cout <<B<<endl;

}