import sys
import math

a = int(input())
ans = 10**100
for i in range(2, 60):
    l = 0
    r = 10**9
    while r - l > 1:
        m = (l + r) // 2
        if m**i >= a:
            r = m
        else:
            l = m
    ans = min(ans, r * i)
print(ans)