# coding: utf-8

import math

def _main():
    x = int(input())
    y = int(input())
    l = int(input())

    turn = 0
    
    move_y = math.ceil(abs(y) / l)
    move_x = math.ceil(abs(x) / l)
    
    if y >= 0:
        turn += move_y
        if x != 0:
            turn += 1
            turn += math.ceil(abs(x) / l)
    else:
        turn += 1
        turn += move_x
        turn += 1
        turn += move_y
    
    print(turn)
    
if __name__ == '__main__':
    _main()