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())
print(1000-(N&1000))
N = int(input())
result = (1000 - N % 1000) % 1000
print(result)
