# -*- coding: utf-8 -*-
"""
No.508 超ゆとり教育
https://yukicoder.me/problems/no/508

"""
import sys
from sys import stdin
from math import sqrt
input = stdin.readline


def main(args):
    n = int(input())
    ans = int(sqrt(n / 3)) + 1000000
    print(ans)


if __name__ == '__main__':
    main(sys.argv[1:])