Go: package main

import (
	"fmt"
	"os"
	"strconv"
	"strings"
	"bufio"
)

var (
	sc = bufio.NewScanner(os.Stdin)
	buf = make([]byte, 1000)
)

func scanText() string{
	sc.Scan()
	return sc.Text()
}

func scanTextArray(n int) []string {
	out := make([]string, n)
	for i, v := range(strings.Split(scanText(), "")) {
		out[i] = v
	}
	return out
}

func scanInt() int {
	out, e := strconv.Atoi(scanText())
	if e != nil {
        panic(e)
    }
	return out
}

func scanIntArray(n int) []int {
	out := make([]int, n)
	for i, v := range(strings.Split(scanText(), " ")) {
		num, e := strconv.Atoi(v)
		if e != nil {
			panic(e)
		}
		out[i] = num
	}
	return out
}
//  template end

var (
	coins = [6]int{500, 100, 50, 10, 5, 1}
)

func f(data int) {
	ans := 0
	change := 1000 - data
	for _, v := range coins {
		for ;v <= change; {
			change -= v
			ans++
		}
	}
	fmt.Println(ans)
}

func main() {
	sc.Buffer(buf, 10000)
	for{
		data := scanInt()
		if data == 0 {
			break
		}
		f(data)
	}
}

C++: #include<bits/stdc++.h>
#define enld '\n'
#define rep(i,n) for(int i=0; i<(n); i++)
using namespace std;
using ll = long long;
using P = pair<int,int>;
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("Ofast")
constexpr ll INF = 1e18;
constexpr int inf = 1e9;
constexpr ll mod = 1000000007;
constexpr ll mod2 = 998244353;
const double PI = 3.1415926535897932384626433832795028841971;
const int dx[6] = {1, 0, -1, 0,1,1};
const int dy[6] = {0, 1, 0, -1,1,-1};
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
// ---------------------------------------------------------------------------

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    vector<int> vec = {500,100,50,10,5,1};
    int N;
    cin >> N;
    while(N != 0){
        N = 1000 - N;
        int ans = 0;
        for(int i=0; i<6; i++){
            while(vec[i] <= N){
                N -= vec[i];
                ans++;
            }
        }
        cout << ans << enld;
        cin >> N;
    }
    return 0;
}

C++: #include <iostream>

using namespace std;

int main()
{
    int x;
    int ans;
    cin >> x;
    while(x!=0) {
        x=1000-x;
        ans=0;
        ans+=x/500;
        x=x%500;
        ans+=x/100;
        x=x%100;
        ans+=x/50;
        x=x%50;
        ans+=x/10;
        x=x%10;
        ans+=x/5;
        x=x%5;
        ans+=x;
        cout << ans << endl;
        cin >> x;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <queue>
#include <vector>
#include <cstdio>
#include <cmath>
#include <cctype>
#define rep(i,a,b) for(int i=(a);i<b;i++)
#define INF 1000000000
#define MAX_N 105
using namespace std;
bool debug=false;

bool check(int n){
  int k=0,x=n;
  while(x){
    k++;
    x/=10;
  }
  if(k==1){
    return true;
  }else if(k==2){
    if(n%10==n/10)return true;
  }else if(k==3){
    if(n%10==n/100)return true;
  }else if(k==4){
    if((n%10==n/1000)&&(n/10%10==n/100%10))return true;
  }
  return false;
}

int main(){
  int n;
  cin>>n;
  for(int i=0;i<1000;i++){
    if(check(n-i)&&n-i>0){
      cout<<n-i<<endl;
      return 0;
    }
    if(check(n+i)&&n<=10000){
      cout<<n+i<<endl;
      return 0;
    }
  }
  return 0;
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <fstream>
using namespace std;

//conversion
//------------------------------------------
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

//math
//-------------------------------------------
template<class T> inline T sqr(T x) {return x*x;}

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<long, long> PLL;
typedef long long LL;
//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))
#define INF 10000000


int main(){
	int n;
	while(cin>>n){
		if(n==0)break;
		int t=1000-n;
		int res=0;
		while(t>=500)res++,t-=500;
		while(t>=100)res++,t-=100;
		while(t>=50)res++,t-=50;
		while(t>=10)res++,t-=10;
		while(t>=5)res++,t-=5;
		res+=t;
		cout<<res<<endl;
	}
	return 0;
}

C++: #include<stdio.h>
int main(void)
{
	int n,a,b,x,y,z,m,i,c,l,k,h,j,r,f;
	scanf("%d",&n);
	a=1000-n;
	b=a/500;
	x=a%500;
	y=x/100;
	z=x%100;
	m=z/50;
	i=z%50;
	l=i/10;
	k=i%10;
	h=k/5;
	j=k%5;
	r=j/1;
	f=j%1;
	c=b+y+m+l+h+r;
	printf("%d\n",c);
	return 0;
}

C++: #include<stdio.h>
int main(void)
{
	int a,s,d,f;
	scanf("%d",&a);
	while(a!=0){
	d=0;
	s=1000-a;
	while(s!=0){
	if(s>=500){
		s=s-500;
		d++;
	}
	else if(s>=100){
		s=s-100;
		d++;
	}
	else if(s>=50){
		s=s-50;
		d++;
	}
	else if(s>=10){
		s=s-10;
		d++;
	}
	else if(s>=5){
		s=s-5;
		d++;
	}
	else if(s>=1){
		s=s-1;
		d++;
	}
	}
	printf("%d\n",d);
	scanf("%d",&a);
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
 
int main(){
  int a,cnt,b,c[5]={500,100,50,10,5};
  while(cin>>a&&a){
    cnt=0;
    b=1000-a;
    for(int i=0;i<5;i++) cnt+=b/c[i],b%=c[i];
    cnt+=b;
    cout<<cnt<<endl;
  }
  return 0;
}

C++: #include<iostream>
using namespace std;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int money = 1000;
	int pay, change, i;

	cin >> pay;
	change = money - pay;

	while(1){
	if(change == 0 || change == 1000) break;
	else if(change < 0 || 1000 < change) break;
	while(1){
		if(change - 500 >= 0){
			i += 1;
			change -= 500;
			break;
		}
		else if(change - 100 >= 0){
			i += 1;
			change -= 100;
			break;
		}
		else if(change - 50 >= 0){
                        i += 1;
                        change -= 50;
                        break;
                }
		else if(change - 10 >= 0){
                        i += 1;
                        change -= 10;
                        break;
                }
		else if(change - 5 >= 0){
                        i += 1;
                        change -= 5;
                        break;
                }
		else{
			i += 1;
			change -= 1;
			break;
		}
	}
	}
	
	if(pay == 0 ) return 0;
        else if(pay < 0 || 1000 < pay) return 0;
	else cout << i << "\n";

	
	return 0;
}