X = abs(int(input()))
Y = int(input())
L = int(input())
C = (X//L)+(Y//L)
if X%L == 1:C+=1
if Y%L == 1:C+=1
if X>0 and Y>0:C += 1
elif X>0 and Y<0:C += 2
elif Y==0 and X>0:C += 1
print(C)