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())

if N % 1000 == 0:
  a = N // 1000
else:
  a = N //1000 + 1
  
print(a*1000 -N)