n = int(input())

res = float('inf')
def p(m, q):
    for i in range(m - 10, m + 10):
        if i < 1:
            continue
        if i ** q >= n:
            return i
    return res

for i in range(1, 70):
    m = int(n ** (1 / i))
    res = min(res, i * p(m, i))
print(res)