x=int(input())
y=int(input())
k=int(input())
c=0
if x>=0 and y<0:
    c+=2
    y*=(-1)

if x<0 and y<0:
    c+=2
    x*=(-1)
    y*=(-1)
if y>=0 and x<0:
    c+=1
    x*=(-1)
if x>0 and y>0:
    c+=1

c+=(x//k)
c+=(y//k)
if x%k!=0:
    c+=1
if y%k!=0:
    c+=1
print(c)