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>
#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};

vector<bool> used;
vector<int> count_t;
vector<bool> isDecided;
vector<int> ans;

int main(){
    while(true){
	int n;
	vector< pair< pair<int,int> , pair<int,int> > > t;
	cin >> n;
	if(n==0) break;
	REP(i,n){
	    int I,A,U,P;
	    cin >> I >> U >> A >> P;
	    t.PB( MP( MP(-A,P) , MP(I,U) ) );
	    sort(ALL(t));
	}
	used = vector<bool>(n*2,false);
	count_t = vector<int>(n*2,0);
	isDecided = vector<bool>(n*2,false);
	ans = vector<int>();

	REP(i,n){
	    if(!used[t[i].second.second-1]){
		used[t[i].second.second-1] = true;
		count_t[t[i].second.second-1]++;
		isDecided[t[i].second.first-1] = true;
		ans.PB(t[i].second.first);
	    }
	}

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


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

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

	sort(ALL(ans));
	REP(i,ans.size()) cout << ans[i] << endl;
    }

    return 0;
}

C++: #define _USE_MATH_DEFINES
#define INF 100000000
#include <iostream>
#include <sstream>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>

using namespace std;

typedef long long ll;
typedef pair <int,int> P;
typedef pair <int,P> PP;

static const double EPS = 1e-8;

const int tx[] = {0,1,0,-1};
const int ty[] = {-1,0,1,0};

class Team{
public:
	int id;
	int univ;
	int success;
	int penalty;

	Team() : id(0),univ(0),success(0),penalty(0){}
	Team(int id,int univ,int success,int penalty){
		this->id = id;
		this->univ = univ;
		this->success = success;
		this->penalty = penalty;
	}
};

class mycmp{
public:
	bool operator()(const Team t1,const Team t2){
		if(t1.success == t2.success
			&& t1.penalty == t2.penalty){
				return (t1.id < t2.id);
		}
		else if(t1.success == t2.success){
			return (t1.penalty < t2.penalty);
		}

		return (t1.success > t2.success);
	}
};

int main(){
	int n;
	while(~scanf("%d",&n)){
		if(n==0) break;
		vector<Team> teams;
		for(int i=0;i<n;i++){
			int ID,U,A,P;
			scanf("%d %d %d %d",&ID,&U,&A,&P);
			teams.push_back(Team(ID,U,A,P));
		}

		map<int,bool> passedTeam;
		map<int,int> univCount;
		sort(teams.begin(),teams.end(),mycmp());
		for(int i=0;i<teams.size();i++){
			if(passedTeam.size() < 10){
				if(univCount[teams[i].univ] < 3){
					passedTeam[teams[i].id] = true;
					printf("%d\n",teams[i].id);
				}
			}
			else if(passedTeam.size() < 20){
				if(univCount[teams[i].univ] < 2){
					passedTeam[teams[i].id] = true;
					printf("%d\n",teams[i].id);
				}
			}
			else if(passedTeam.size() < 26){
				if(univCount[teams[i].univ] < 1){
					passedTeam[teams[i].id] = true;
					printf("%d\n",teams[i].id);
				}
			}
		}
	}
}

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

class Team {
public:
    int i, u, a, p;

    friend bool operator< (const Team &t1, const Team &t2) {
        return (t1.a > t2.a) || (t1.a == t2.a && t1.p < t2.p) || (t1.a == t2.a && t1.p == t2.p && t1.i < t2.i);
    }
};

const int U_MAX = 1000;
int us[U_MAX];

int main() {
    int n;
    while (cin >> n, n) {
        vector<Team> ts(n);
        for (int i = 0; i < n; i++) {
            cin >> ts[i].i >> ts[i].u >> ts[i].a >> ts[i].p;
        }
        sort(ts.begin(), ts.end());
        fill_n(us, U_MAX, 0);
        int elect = 0;
        for (int i = 0; i < n; i++) {
            if (elect < 10) {
                if (us[ts[i].u]++ < 3) {
                    cout << ts[i].i << endl;
                }
            } else if (elect < 20) {
                if (us[ts[i].u]++ < 2) {
                    cout << ts[i].i << endl;
                }

            } else if (elect < 26) {
                if (us[ts[i].u]++ < 1) {
                    cout << ts[i].i << endl;
                }
            } else {
                break;
            }
        }
    }
}