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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict";

const main = arg => {
    const N = arg.split("\n")[0];
    const powerOf = [1]; 
    
    for(let i=2; i<=32; i++) {
        let pow = 2;
        while(Math.pow(i, pow) < N) {
            powerOf.push(Math.pow(i,pow));
            pow++;
        }
    }
    
    console.log(Math.max(...powerOf));
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));