#				 Author: Udit "luctivud" Gupta @ https://www.linkedin.com/in/udit-gupta-1b7863135/					 #


import math;   		from collections import *
import sys;   		from functools import reduce
import time;   		from itertools import groupby

# sys.setrecursionlimit(10**6)

# def input()         : return sys.stdin.readline()
def get_ints()      : return map(int, input().strip().split())
def get_list()      : return list(get_ints())
def get_string()    : return list(input().strip().split())
def printxsp(*args) : return print(*args, end="")
def printsp(*args)  : return print(*args, end=" ")


DIRECTIONS = [(+0, +1), (+0, -1), (+1, +0), (+1, -1)] 
NEIGHBOURS = [(-1, -1), (-1, +0), (-1, +1), (+0, -1),\
              (+1, +1), (+1, +0), (+1, -1), (+0, +1)]



# MAIN >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

# for _test_ in range(int(input())): 


a = int(input())
ans = float('inf')
i = 2
while (i**4) <= a:
	temp = a
	j = 0
	while temp > 0:
		temp //= i
		j += 1
	ans = min(ans, i*j)
	i += 1
print(ans)