Go: package main

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

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	for n := getNextInt(scanner); n > 0; n = getNextInt(scanner) {
		tt := make([]team, n)
		for i := 0; i < n; i++ {
			tt[i].id = getNextInt(scanner)
			tt[i].uni = getNextInt(scanner)
			tt[i].ac = getNextInt(scanner)
			tt[i].pn = getNextInt(scanner)
		}
		sort.SliceStable(tt, func(i, j int) bool {
			if tt[i].ac == tt[j].ac {
				if tt[i].pn == tt[j].pn {
					return tt[i].id < tt[j].id
				}
				return tt[i].pn < tt[j].pn
			}
			return tt[i].ac > tt[j].ac
		})
		cc := make([]int, 100005)
		ans := make([]int, 0)
		for i := 0; i < n; i++ {
			if cc[0] < 10 && cc[tt[i].uni] < 3 {
				cc[0]++
				cc[tt[i].uni]++
				ans = append(ans, tt[i].id)
				continue
			}
			if cc[0] < 20 && cc[tt[i].uni] < 2 {
				cc[0]++
				cc[tt[i].uni]++
				ans = append(ans, tt[i].id)
				continue
			}
			if cc[0] < 26 && cc[tt[i].uni] < 1 {
				cc[0]++
				cc[tt[i].uni]++
				ans = append(ans, tt[i].id)
				continue
			}
		}
		for i := 0; i < len(ans); i++ {
			fmt.Fprintln(writer, ans[i])
		}
	}
}

type team struct {
	id, uni, ac, pn int
}

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

#define rep(X,Y) for(int (X) = 0; (X) < (Y); ++(X))
typedef long long ll;
typedef pair<int, int> pii;

#define all(X) (X).begin(),(X).end()
#define pb push_back
#define eb emplace_back
#define rrep(X,Y) for(int (X)=(Y)-1; (X) >= 0; --(X))
#define X first
#define Y second
#define reps(X,Y,Z) for(int (X)=(Y); (X) <= (Z); ++(X))
#define sz size()
#define in(i,j,k) ((i) >= (j) && (j) <= (k))

#define UNIQUE(X) (X).erase(unique(all(X)), (X).end())

int main(){
    int n;
    while(cin >> n&&n){
        vector<pair<pii,pii > > v;
        rep(i,n){
            int id,u,a,p;
            cin >> id >> u >> a >> p;
            v.eb(pii(-a,p),pii(id,u));
        }
        sort(all(v));
        map<int,int> m;
        vector<int> ans;
        rep(i,n){
            if( ans.sz < 10 && m[v[i].Y.Y] < 3 ||
                ans.sz < 20 && m[v[i].Y.Y] < 2 ||
                ans.sz < 26 && m[v[i].Y.Y] < 1 )
            {
                m[v[i].Y.Y]++;
                ans.pb(v[i].Y.X);
            }
        }
        rep(i,ans.sz){
            cout << ans[i] << endl;
        }
    }
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <queue>
#include <stack>
#include <vector>
#include <algorithm>
#include <string>
#include <cstring>
#include <cmath>
#include <complex>
#include <map>
#include <climits>
#include <sstream>
using namespace std;

#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define EPS 1e-8
#define F first
#define S second
#define mkp make_pair

static const double PI=6*asin(0.5);
typedef long long ll;
typedef complex<double> CP;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vint;
static const int INF=1<<24;

template <class T>
void initvv(vector<vector<T> > &v,int a,int b, const T  &t = T()){
	v.assign(a,vector<T>(b,t));
}

//v.erase(unique(v.begin(),v.end()),v.end());


int main(){
	int n;
	while(cin>>n,n){
		vector<pair<pii,pii> > v;
		vint tt(2000,0);
		rep(i,n){
			int a,b,c,d;
			cin>>a>>b>>c>>d;
			v.PB(mkp(mkp(100-c,d),mkp(a,b)));
		}
		sort(ALL(v));
		// rep(i,n){
			// cout<<v[i].S.F<<" "<<v[i].S.S<<endl;
		// }
		int cnt=0;
		rep(i,n){
			bool f=false;
			if(cnt<10&&tt[v[i].S.S]<3){
				f=true;
			}
			else if(cnt<20&&tt[v[i].S.S]<2){
				f=true;
			}
			else if(cnt<26&&tt[v[i].S.S]<1){
				f=true;
			}
			if(f){
				cnt++;
				tt[v[i].S.S]++;
				cout<<v[i].S.F<<endl;
			}
		}
	}
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define MP make_pair
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define CLR(a) memset(a,0,sizeof(a))
#define SET(a,c) memset(a,c,sizeof(a))

#define DEBUG(x) cout<<"#x"<<": "<<x<<endl

using namespace std;

typedef long long int ll;
typedef vector<int> vi;
typedef vector<ll> vl;

const ll INF = INT_MAX/3;
const ll MOD = 1000000007;
const double EPS = 1e-14;
const int dx[] = {1,0,-1,0} , dy[] = {0,1,0,-1};

map<int,bool> used;
map<int,int> count_t;
map<int,bool> isDecided;

int main(){
    while(true){
	int n;
	vector< pair< pair<int,int> , pair<int,int> > > t;
	cin >> n;
	if(n==0) break;
	used.clear();
	count_t.clear();
	isDecided.clear();
	REP(i,n){
	    int I,A,U,P;
	    cin >> I >> U >> A >> P;
	    t.PB( MP( MP(-A,P) , MP(I,U) ) );
	    used[I] = false;
	    count_t[U] = false;
	    isDecided[I] = false;
	}
	sort(ALL(t));
// 	REP(i,n) printf("A: %d P: %d I: %d U: %d\n",-t[i].first.first,t[i].first.second,t[i].second.first,t[i].second.second);
	int temp = 0;
//
// 	REP(i,n){
// 	    if(!used[t[i].second.second]){
// 		used[t[i].second.second] = true;
// 		count_t[t[i].second.second]++;
// 		isDecided[t[i].second.first] = true;
// 		temp++;
// 	    }
// 	}

	if(temp < 10){
	    REP(i,n){
		if(!isDecided[t[i].second.first] && count_t[t[i].second.second] < 3){
		    count_t[t[i].second.second]++;
		    isDecided[t[i].second.first] = true;
		    temp++;
		    i=-1;
		}
		if(temp == 10) break;
	    }
	}


	if(temp < 20){
	    REP(i,n){
		if(!isDecided[t[i].second.first] && count_t[t[i].second.second] < 2){
		    count_t[t[i].second.second]++;
		    isDecided[t[i].second.first] = true;
			temp++;
		    i=-1;
		}
		if(temp == 20) break;
	    }
	}

	if(temp < 26){
	    REP(i,n){
		if(!isDecided[t[i].second.second] && count_t[t[i].second.second] < 1){
		    count_t[t[i].second.second]++;
		    isDecided[t[i].second.first] = true;
		    temp++;
		    i=-1;
		}
		if(temp == 26) break;
	    }
	}

	REP(i,n){
	    if(isDecided[t[i].second.first]) cout << t[i].second.first << endl;
	}
    }

    return 0;
}