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 Python (3.8.2) (judge verdict: Wrong Answer)

#!/usr/bin/env python3

def solve(x):
    if x == 1:
        return 1
    f = 2
    l = [1]
    while f * f <= x:
        d = f
        while d <= x:
            l.append(d)
            d *= d
        f += 1
    return max(l)



def main():
    X = int(input())
    print(solve(X))
    return

if __name__ == '__main__':
    main()