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(N%1000)
N = int(input())

temp = N%1000

if temp == 0:
    print(str(0))
else:
    print(1000-N%1000)