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())

import math

print(int(math.ceil(N)) - N)
N = int(input())

if N % 1000 == 0:
  print("0")
elif N < 1000:
  print(1000-N)
else:
  n = list(str(N))
  print(1000*(1+int(n[0]))-N)