#!/usr/bin/env python3
# -*- coding: utf-8-*-
if __name__ == '__main__':
    x = int(input())
    y = int(input())
    l = int(input())
    if y < 0:
        a = 2
    elif x == 0:
        a = 0
    else:
        a = 1
    a += abs(x) // l
    if abs(x) % l > 0:
        a += 1
    a += abs(y) // l
    if abs(y) % l > 0:
        a += 1
    print(a)