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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <cmath>
using namespace std;

int main(void)
{
    int x;
    cin >> x;

    int max = 0;
    int i, j;
    for (i = 1; i <= x; i++) {
        for (j = 2; j <= x; j++) {
            if (pow(i, j) <= x) {
                if (max < pow(i, j)) {
                    max = pow(i, j);
                }
            }
            else
                break;
        }
    }
    cout << max << endl;
    return 0;
}