# -*- coding:utf-8 -*-
import math

if __name__ == '__main__':
    x, y, l = (int(input()) for x in range(3))
    r = min((x != 0) + (y < 0) * 2, 2)
    x, y = map(abs, (x, y))
    print(sum(map(math.ceil, (r, x / l, y / l))))