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.

Examples

Input

10


Output

9


Input

1


Output

1


Input

999


Output

961
import math

x = int(raw_input())
rmax = 1
lmax = int(math.ceil(math.sqrt(x)))
for j in range(2, lmax):
    for k in range(2, 10 + 1):
        r = j ** k
        if r > x:
            break
        else:
            if r > rmax:
                rmax = r

print rmax