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 - N%1000)
N = int(input())
i = 0
while True:
    i += 1000
    if i >= N:
        break
print(i - N)