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 <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define rep(i,h) for(int i = 0; i < h; ++i)
#define rep1(i,h) for(int i = 0; i <= h; ++i)
#define rep2(i,n,h) for(int i = n; i < h; ++i)
#define rep3(l,n,h) for(int l = n; l <= h; ++l)
typedef pair<int,int> int_pair;
typedef pair<string,string> string_pair;


int main(void) {
    double x,ans = 0;
    cin >> x;
    for(double i = 1; i < x; i++) {
        for(double j = 2; j < x; j++) {
            double res = pow(i,j);
            if (res < x) {
                ans = max(ans, res);
            }
        }
    }
    cout << ans << endl;

}