def steps(distance, stride):
    distance = abs(distance)
    return distance // stride if distance % stride == 0 else distance // stride + 1

X = int(input())
Y = int(input())
L = int(input())
if X != 0 and Y >= 0:
    print(steps(Y, L) + 1 + steps(X, L))
elif X == 0 and Y >= 0:
    print(steps(Y, L))
elif X != 0 and Y < 0:
    print(1 + steps(X, L) + steps(Y, L))
elif X == 0 and Y < 0:
    print(1 + 1 + steps(Y, L))