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
#abc097b

x=int(raw_input())
r=[]
for i in xrange(1,32):
 for j in xrange(2,32):
  if i**j<=1000:
   r.append(i**j)
r2=[]
for i in xrange(len(r)):
 y=x-r[i]
 if y>=0:
  r2.append(r[i])
print max(r2)
