#!/usr/bin/env pypy3

A = int(input())

def y_given_x(x, A):
	ret = 0
	while x**ret < A:
		ret += 1
	return ret

s1 = 2*y_given_x(2, A)
s2 = 3*y_given_x(3, A)

print(min(s1, s2))