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: Wrong Answer)

# coding: utf-8
# Your code here!

INPUT=int(input())
b=1
p=2
END=0

while True: 
    while True: 
        now_num = b**p
        if b == 1:
            end_num=now_num
            break
        elif p==2 and INPUT < now_num:
            END = 1
            break
        elif INPUT < now_num:
            end_num = b**(p-1)
            break
        else:
            p+=1
        
    if END == 1:
        ans=end_num
        break
    b+=1
    p=2
    
print(ans)