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: Runtime Error)

import sys
import math
import itertools as it
def I():return int(sys.stdin.readline().replace("\n",""))
def I2():return map(int,sys.stdin.readline().replace("\n","").split())
def S():return str(sys.stdin.readline().replace("\n",""))
def L():return list(sys.stdin.readline().replace("\n",""))
def Intl():return [int(k) for k in sys.stdin.readline().replace("\n","").split()]
def Lx(k):return list(map(lambda x:int(x)*-k,sys.stdin.readline().replace("\n","").split()))

if __name__ == "__main__":
    l = [i*i for i in range(1,int(math.sqrt(1000))+1)]
    x = I()
    i = 0
    while l[i] <= x:
        i += 1
    print(l[i-1])