Problem:
Score : 100 points

Problem Statement

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.

Constraints

1 \leq N \leq 10000

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the amount of change as an integer.

Sample Input 1

1900

Sample Output 1

100

We will use two 1000-yen bills to pay the price and receive 100 yen in change.

Sample Input 2

3000

Sample Output 2

0

We can pay the exact price.

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const int INF = 1e9;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	
	// int t;
	// cin>>t;
	// while(t--){
		int n;
		cin>>n;
		n %= 1000;
		if (n == 0){
			cout<<0<<'\n';
		}else{
			cout<<1000-n<<'\n';
		}
	// }
	return 0;
}