ans = 0
x,y,k = int(input()),int(input()),int(input())
ans += ((y<0)+(x!=0)+(y<0 and x==0))
x,y,k = map(abs,(x,y,k))
a,b = x//k,y//k
ans += (a*k!=x)+(b*k!=y)
ans += a + b
print(ans)