// *************Template Starts Here**********************
#pragma comment(linker, "/stack:640000000")

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <iomanip>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

const double EPS = 1e-9;
const int INF = 0x7f7f7f7f;
const double PI = acos(-1.0);

#define    READ(f)           freopen(f, "r", stdin)
#define    WRITE(f)          freopen(f, "w", stdout)
#define    MP(x, y)          make_pair(x, y)
#define    PB(x)             push_back(x)
#define    rep(i,n)          for(int i = 1 ; i<=(n) ; i++)
#define    repI(i,n)         for(int i = 0 ; i<(n) ; i++)
#define    FOR(i,L,R)        for (int i = L; i <= R; i++)
#define    ROF(i,L,R)        for (int i = L; i >= R; i--)
#define    FOREACH(i,t)      for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define    ALL(p)            p.begin(),p.end()
#define    ALLR(p)           p.rbegin(),p.rend()
#define    SET(p)            memset(p, -1, sizeof(p))
#define    CLR(p)            memset(p, 0, sizeof(p))
#define    MEM(p, v)         memset(p, v, sizeof(p))
#define    getI(a)           scanf("%d", &a)
#define    getII(a,b)        scanf("%d%d", &a, &b)
#define    getIII(a,b,c)     scanf("%d%d%d", &a, &b, &c)
#define    getL(a)           scanf("%lld",&a)
#define    getLL(a,b)        scanf("%lld%lld",&a,&b)
#define    getLLL(a,b,c)     scanf("%lld%lld%lld",&a,&b,&c)
#define    getC(n)           scanf("%c",&n)
#define    getF(n)           scanf("%lf",&n)
#define    getS(n)           scanf("%s",n)
#define    bitCheck(N,in)    ((bool)(N&(1<<(in))))
#define    bitOff(N,in)      (N&(~(1<<(in))))
#define    bitOn(N,in)       (N|(1<<(in)))
#define    iseq(a,b)          (fabs(a-b)<EPS)
#define    ff    first
#define    ss    second
#define    ll    long long
#define    ull   unsigned long long


typedef pair<int, int>pii;
typedef vector<pii>vpii;
typedef vector<int>vi;
typedef vector<vi>vii;


template< class T > inline T _abs(T n) { return ((n) < 0 ? -(n) : (n)); }
template< class T > inline T _max(T a, T b) { return (!((a) < (b)) ? (a) : (b)); }
template< class T > inline T _min(T a, T b) { return (((a) < (b)) ? (a) : (b)); }
template< class T > inline T _swap(T &a, T &b) { a = a ^ b; b = a ^ b; a = a ^ b;}
template< class T > inline T gcd(T a, T b) { return (b) == 0 ? (a) : gcd((b), ((a) % (b))); }
template< class T > inline T lcm(T a, T b) { return ((a) / gcd((a), (b)) * (b)); }
template <typename T> string NumberToString ( T Number ) { ostringstream ss; ss << Number; return ss.str(); }

#ifdef howcum
#define debug(args...) {cerr<<"Debug: "; dbg,args; cerr<<endl;}
#else
#define debug(args...)  // Just strip off all debug tokens
#endif

struct debugger {
	template<typename T> debugger& operator , (const T& v) {
		cerr << v << " ";
		return *this;
	}
} dbg;

//// 4 direction
//int dx[]={-1,1,0,0};
//int dy[]={0,0,-1,1};
//
//// 8 direction
//int dx[]={-1,1,0,0,-1,-1,1,1};
//int dy[]={0,0,-1,1,-1,1,1,-1};
//
//// horse
//int dx[] = {-2,-2,2,2,-1,-1,1,1};
//int dy[] = {1,-1,-1,1,2,-2,-2,2};


int main() {
#ifdef trifiasco
	READ("in");
	WRITE("out");
#endif // trifiasco
	ios_base::sync_with_stdio(0); cin.tie(0);

	int n;
	while (cin >> n)
	{
		int bills = (abs (1000 - (n % 1000))) % 1000;

		cout << bills << endl;
	}

	return 0;
}


Measured memory_bytes: 3612