import math


def main():
    x = int(input())
    y = int(input())
    l = int(input())

    ans = math.ceil(abs(x) / l) + math.ceil(abs(y) / l)
    if y < 0:
        ans += 2
    elif x != 0:
        ans += 1

    print(ans)
    
    
if __name__ == '__main__':
    main()