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

A = -(-abs(X) // L)
B = -(-abs(Y) // L)
C = 0

if X == 0 and Y < 0: #南
    C = 2
elif X < 0 and Y < 0: #南西
    C = 2
elif X > 0 and Y < 0: #南東
    C = 2
elif X > 0 and Y == 0: #東
    C = 1
elif X > 0 and Y > 0: #北東
    C = 1
elif X == 0 and Y > 0: #北
    C = 0
elif X < 0 and Y > 0: #北西
    C = 1
elif X < 0 and Y == 0: #西
    C = 1

print(A + B + C)