# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")
import copy

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	X = int(input())
	Y = int(input())
	L = int(input())
	state = 0
	if X != 0:
		state = 1
	if Y < 0:
		state = 2

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


if __name__ == '__main__':
	main()