X = int(input())
Y = int(input())
L = int(input())
ans = (abs(X)+L-1)//L + (abs(Y)+L-1)//L
if X == 0:
    if Y < 0:
        ans += 2
else:
    if Y >= 0:
        ans += 1
    else:
        ans += 2
print(ans)