import math

X = int(input())
Y = int(input())
L = int(input())

if(X == 0):
	if(Y >= 0):
		turn = 0
	else:
		turn = 2
else:
	if(Y >= 0):
		turn = 1
	else:
		turn = 2
	
print(turn + math.ceil(abs(X)/L) + math.ceil(abs(Y)/L))