p=[int(input()) for i in range(2)]
x,y=map(abs,p)
l=int(input())
r=0
r+=x//l if x%l==0 else x//l +1
r+=y//l if y%l==0 else y//l +1
if p[1] >= 0:
    r+=0 if x==0 else 1
else:
    r+=1 if y==0 else 2
print(r)