from math import ceil, fabs
f = lambda : int(input())
x, y, l = f(), f(), f()
ans = 0
if y < 0:
	if x != 0: ans += 1
	else: ans += 2
else:
	if x != 0: ans += 1
print(ans + ceil(fabs(x)/l) + ceil(fabs(y)/l))