step = 0
x = abs(int(input()))
y = int(input())
if y<0: step += 2
y = abs(y)
l = abs(int(input()))
step += int(x/l) + int(y/l)
if x%l>0: step += 1
if y%l>0:	step += 1
if x*y>0: step += 1
print(step)