import math
def main():
    x = int(input())
    y = int(input())
    l = int(input())
    count = 0
    if x != 0:
        count += 1
    if y < 0:
        count += 2
    count += math.ceil(abs(x / l))
    count += math.ceil(abs(y / l))

    print(count)

if __name__ == "__main__":
    main()