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())
while N>=1000:
    N-=1000
print(N)
N=int(input())
if N%1000==0:
    print(0)
else:
    while N>=0:
        N-=1000
    print(abs(N))