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: Accepted)

#include<iostream>
#include<algorithm>
#include<string>
using namespace std;

int main(){
    int x;
    cin >> x;
    int max = 0;
    if(x==1){
        cout << x << endl;
    }else{
    for(int i=1;i<x;i++){
        int a=i;
        for(int j=0;j<x;j++){
            a*=i;
            if(a>x){
                break;
            }else if(max<a){
                max = a;
            }
        }
    }
    cout << max << endl;
    }
}