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

def solve(X, Y, L):
    X = abs(X)
    n = 0
    if Y < 0:
        if X == 0:
            n += 2
        else:
            n += 1
        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))