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)

x = int(input())

sosu = [2,3,5,7,11,13,17,19,23,29,31]

if(x==1):
  print(1)
else:
  ans = 1
  for i in range(len(sosu)):
    now = sosu[i]
    for j in range(1,11):
      now = now*sosu[i]
      if(now <= x and ans <= now):
        ans = now
      elif(now >= x):
        break

print(ans)