x, y, l = int(input()), int(input()), int(input())

def calc(x, y, l):
    cnt = 0
    if x!=0 and y>0:
        cnt+=1
    if y==0 and x!=0:
        cnt+=1
    if y<0:
        cnt+=2
    cnt += abs(x)//l
    if abs(x)%l>0:cnt+=1
    cnt += abs(y)//l
    if abs(y)%l>0:cnt+=1
    return cnt
print(calc(x, y, l))