# coding: utf-8
import array, bisect, collections, heapq, itertools, math, random, re, string, sys, time
sys.setrecursionlimit(10 ** 7)
INF = 10 ** 20
MOD = 10 ** 9 + 7
 
 
def II(): return int(input())
def ILI(): return list(map(int, input().split()))
def IAI(LINE): return [ILI() for __ in range(LINE)]
def IDI(): return {key: value for key, value in ILI()}
 
 
def solve(n):
    ans = int(math.sqrt(n // 3))
    if ans < 1:
        ans = 1
    return ans

 
def main():
    n = II()
    print(solve(n))
 
 
if __name__ == "__main__":
    main()