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.
from typing import List
N = int(input())

print(N-N%1000)
from typing import List
N = int(input())
if(N%1000==0):
    X = N//1000
    print(1000*(X)-N)
else:
    X = N//1000
    print(1000*(X+1)-N)