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

# X方向の移動回数
move_x = (abs(X) + L - 1) // L

# Y方向の移動回数
move_y = (abs(Y) + L - 1) // L

count = move_x + move_y

# 方向転換
if (Y < 0) and (X != 0):
    count += 2
elif (Y >= 0) and (X != 0):
    count += 1
else:
	pass

print(count)