import math
X=int(input())
Y=int(input())
L=int(input())
turn =0
sum =0
if Y<0:
    turn =2
elif X==0:
    turn =0
else:
    turn =1
X=abs(X)
Y=abs(Y)
sum = sum+math.ceil(X/L)
sum = sum+math.ceil(Y/L)
print(turn+sum)