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.
import numpy as np

N = int(input())

print(1000 * np.ceil(N/1000) - N)
import numpy as np

N = int(input())

print(int(1000 * np.ceil(N/1000) - N))