import math

distination_x = float(input())
distination_y = float(input())
distance = float(input())

turn = int(0)

if distination_y >= 0 and distination_x >= 0:
    turn = math.ceil(distination_y / distance) + math.ceil(distination_x/distance) + 1

elif distination_y >= 0 and distination_x < 0:
    turn = math.ceil(distination_y/distance) + math.ceil(-1*distination_x/distance) + 1

elif distination_y < 0 and distination_x >= 0:
    turn = math.ceil(-1*distination_y/distance) +2 +math.ceil(distination_x/distance) +1

elif distination_y < 0 and distination_x < 0:
    turn = math.ceil(-1*distination_y/distance) +2 +math.ceil(distination_x/distance) +1

if distination_x == 0:
    turn = turn-1

print(turn)