import sys
def input(): return sys.stdin.readline().strip()
def mapint(): return map(int, input().split())
sys.setrecursionlimit(10**9)

A = int(input())
ans = 10**10
for i in range(2, 1081):
    l, r = 0, 100
    if i>=A:
        ans = min(i, ans)
        break
    while l+1<r:
        half = -(-(l+r)//2)
        if i**half>=A:
            r = half
        else:
            l = half
    ans = min(ans, r*i)
print(ans)