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

def solve(X, Y, L):
    X = abs(X)
    Y = abs(Y)
    n = Y // L + (1 if Y % L else 0)
    if X == 0:
        return n
    n += 1
    n += X // L + (1 if X % L else 0)
    return n

print(solve(X, Y, L))