We will buy a product for N yen (the currency of Japan) at a shop.  If we use only 1000-yen bills to pay the price, how much change will we receive?  Assume we use the minimum number of bills required.
n = int(input())
n1 = n%1000

if n1 == 0:
    print(0)
else:
    print(1000-n)
n = int(input())
n1 = n%1000

if n1 == 0:
    print(0)
else:
    print(1000-n1)