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
#coding:utf-8


X = int(raw_input())


lists = []

for i in range(11, 32):
    lists.append(i ** 2)

for i in range(6, 11):
    lists.append(i ** 2)
    lists.append(i ** 3)

for i in range(4, 6):
    lists.append(i ** 2)
    lists.append(i ** 3)
    lists.append(i ** 4)

for i in range(3, 4):
    lists.append(i ** 2)
    lists.append(i ** 3)
    lists.append(i ** 4)
    lists.append(i ** 5)

for i in range(1, 10):
    lists.append(2 ** i)

lists.append(1)

max_num = 0
for i in lists:
    if (max_num < i) and (i <= X):
        max_num = i

print max_num
