import sys


def input(): return sys.stdin.readline().rstrip()


def main():
    X = int(input())
    Y = int(input())
    L = int(input())
    ans = 0
    if X != 0:
        ans = 1
    if Y < 0:
        ans = 2

    print(ans + (abs(X)+L-1)//L+(abs(Y)+L-1)//L)


if __name__ == '__main__':
    main()