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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<double,int> pdi;
typedef pair<double,double> pdd;
typedef pair<double,ll> pdl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vii;
typedef vector<pll> vll;
typedef vector<vl> vvl;
typedef vector<vi> vvi;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<pdd> vdd;
typedef vector<pdi> vdi;
typedef vector<pdl> vdl;
#define fi first
#define se second
const ll INFLL=LLONG_MAX;
const int INF=INT_MAX;
const ll MAXLL=0x3f3f3f3f3f3f3f3f;
const int MAX=0x3f3f3f3f;
#define eb emplace_back
#define emp emplace
#define mp(a,b) make_pair(a,b)
template<class T> using min_heap=priority_queue<T,vector<T>,greater<T> >;
template<class T>
void sort(vector<T>& v){
	sort(v.begin(),v.end());
}
template <class T, class U>
void sort(vector<T>& v,U func){
	sort(v.begin(),v.end(),func);
}
template<class T>
void rsort(vector<T>& v){
	sort(v.rbegin(),v.rend());
}
template <class T>
int lb_index(vector<T>& v,T k){
	return lower_bound(v.begin(),v.end(),k)-v.begin();
}
template <class T>
int ub_index(vector<T>& v,T k){
	return upper_bound(v.begin(),v.end(),k)-v.begin();
}
template<class T>
bool is_sorted(vector<T>& v){
	return is_sorted(v.begin(),v.end());
}
template<class T>
bool sorted(vector<T>& v){
	return is_sorted(v);
}

void solve(){
	int n;
	cin>>n;
	cout<<1000-(n%1000);
}

int main(){
	ios::sync_with_stdio(0);
	int numberofsubtestcases=1;
//	cin>>numberofsubtestcases;
	while(numberofsubtestcases--){
		solve();
	}
}