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
lst = [1]
X = int(raw_input())

cnt = 2
now = 4
while cnt <= X:
	if now <= X and now not in lst:
		lst.append(now)
		now = now * cnt
	else:
		cnt = cnt + 1
		now = cnt * cnt
lst.sort()
print lst[-1]