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.
price = int(input())
print(price%1000)

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