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
def f(x):
  s = set()
  s.add(1)
  for b in xrange(2, x+1):
    y = b
    for p in xrange(x+1):
      y *= b
      if y > x: break
      s.add(y)
  l = sorted(list(s))
  return l[-1]
  
X=int(raw_input())
print f(X)