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>

using namespace std;

int main(){
    int x;
    cin >> x;
    int kazu=0;
    int ans=1;
    if(x<=3){
        cout << "1" <<endl;
        return 0;
    }
    for(int l=2;l<x;l++){
        kazu=l;
        while(kazu<x){
            kazu*=l;
        }
        ans=max(ans,kazu/l);
    }
    cout << ans << endl;
    return 0;
}