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 (3.4.3) (judge verdict: Runtime Error)

def main():
    n = int(input())

    # for i in range(1, n + 1):
    #     if

    # i = 1
    # while i * i <= n:
    #     i += 1
    #
    # print((i - 1) ** 2)

    ans = [1]
    for i in range(2, n + 1):
        j = 2
        while i ** j <= n:
            ans.append(i ** j)
            j += 1

    print(max[ans])


if __name__ == '__main__':
    main()