def main():
    x = int(input())
    y = int(input())
    l = int(input())
    count = 0
    if x < 0:
        count += 1
    if y < 0:
        count += 1
    distance = abs(x) + abs(y)
    
    if distance % l == 0:
        count = count + (distance // l)
    elif distance % l > 0:
        count = count + (distance // l) + 1
    print(count)

if __name__ == "__main__":
    main()