X = int(input())
Y = int(input())
L = int(input())

import math
if X == 0 and Y == 0:
    print(0)
elif X == 0 and Y > 0 :
    y = math.ceil(Y / L)
    print(y)
elif X == 0 and Y < 0:
    y = math.ceil(abs(Y) / L)
    print(y + 2)
elif X > 0 and Y == 0:
    x = math.ceil(X / L)
    print(x + 1)
elif X > 0 and Y > 0:
    x = math.ceil(X / L)
    y = math.ceil(Y / L)
    print(x + y + 1)
elif X > 0 and Y < 0:
    x = math.ceil(X / L)
    y = math.ceil(abs(Y) / L)
    print(x + y + 2)
elif X < 0 and Y == 0:
    x = math.ceil(abs(X) / L)
    print(x + 1)
elif X < 0 and Y > 0:
    x = math.ceil(abs(X) / L)
    y = math.ceil(Y / L)
    print(x + y + 1)
elif X < 0 and Y < 0:
    x = math.ceil(abs(X) / L)
    y = math.ceil(abs(Y) / L)
    print(x + y + 2)