ans = 0
x,y,k = int(input()),int(input()),int(input())
if (y<0 and k>0)or(y>0 and k<0):
    ans += 2
if x!=0:
    ans += 1
x,y,k = map(abs,(x,y,k))
a,b = x//k,y//k
if a*k!=x:
    a+=1
if b*k!=y:
    b+=1
ans += a + b
print(ans)