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

res = 0

if Y < 0:
    res += 1
    Y = abs(Y)
else:
    pass
if Y % L != 0:
    ycount = Y // L + 1
else:
    ycount = Y // L

res += ycount

if X < 0:
    res += 1
    X = abs(X)
else:
    pass
if X % L != 0:
    xcount = X // L + 1
else:
    xcount = X // L

res += xcount

print(res)