import math
x=int(input())
y=int(input())
l=int(input())
if y>=0 and x!=0:
	count = math.ceil(abs(x)/l)+math.ceil(abs(y)/l)+1
elif y>=0 and x==0:
	count = math.ceil(abs(y)/l)
else:
	count = math.ceil(abs(x)/l)+math.ceil(abs(y)/l)+2
print(count)