# 自作ライブラリ
# https://github.com/takumi-okamoto/competitive-programming-public/tree/main/mylib

import sys


# sys.setrecursionlimit(10**8)


def debug(*args):
    print(*args, file=sys.stderr)


def main():
    n = int(input())
    if n < 100:
        print(0)
        return
    ok = 10**9
    ng = 0
    while ok - ng > 1:
        mid = (ok + ng) // 2
        s = mid * 500
        if n - s < 100:
            ok = mid
        else:
            ng = mid
    print(ok)


if __name__ == "__main__":
    main()