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
# 1
# 4 8 16 32 64 128 256 512
# 9 27 81 243 729
# 14 64 256
# 25 125 625
# 36 216
# 49 343
# 64 512
# 81 729
# 100
# 121
# .. 
# 961

X = int(raw_input())

array = []
num=1
i=1
p=2
while i <= 31:
    p = 2
    while p < 9:
        tmp = pow(i, p);
        if tmp <= 1000:
            array.append(tmp)
        else:
            break

        p = p +1
    i = i+1
        
array.sort()
array.reverse()

#print array

for item in array:
    if X < item:
        continue
    else:
        print item
        break
