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 <iostream>
#include <vector>
#include <algorithm>
#include <map>

using namespace std;

class teamInfo{
public:
	int id;
	int u;
	int a;
	int p;

	bool operator<(const teamInfo &ti)const{
		if(ti.a < this->a)
			return true;
		else if(ti.a > this->a)
			return false;
		else{
			if(ti.p < this->p)
				return false;
			else if(ti.p > this->p)
				return true;
			else{
				if(ti.id > this->id)
					return true;
				else
					return false;
			}
		}
	}
};

int main(){

	int n;
	while(cin >> n && n !=0){
		vector<teamInfo> v;
		map<int,int> ucnt;

		for(int i = 0; i < n; i++){
			teamInfo ti;
			cin>>ti.id>>ti.u>>ti.a>>ti.p;
			v.push_back(ti);
		}
		sort(v.begin(),v.end());

		int team=0;
		for(int i = 0; i < n; i++){
			if(team < 10){
				ucnt[v[i].u]++;
				if(ucnt[v[i].u] >= 4){
					ucnt[v[i].u]--;
				}
				else{
					cout << v[i].id << endl;
					team++;
				}
			}
			else if(team < 20){
				ucnt[v[i].u]++;
				if(ucnt[v[i].u] >= 3){
					ucnt[v[i].u]--;
				}
				else{
					cout << v[i].id << endl;
					team++;
				}
			}
			else if(team < 26){
				ucnt[v[i].u]++;
				if(ucnt[v[i].u] >= 2){
					ucnt[v[i].u]--;
				}
				else{
					team++;
					cout << v[i].id << endl;
				}
			}
		}
	}

	return 0;
}

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

typedef struct
{
  int I, U, A, P;
} Team;

class solve
{
public:
  bool operator()(const Team& lhs, const Team& rhs)
  {
    if (lhs.A == rhs.A)
      return lhs.P < rhs.P;
    return lhs.A > rhs.A;
  }
};

int main()
{
  int n;
  while (cin >> n) {
    if (n == 0)
      break;

    vector<Team> team(n);
    for (int i = 0; i < n; ++i)
      cin >> team[i].I >> team[i].U >> team[i].A >> team[i].P;
    sort(team.begin(), team.end(), solve());

    int advance = 0;
    vector<int> univ(1000, 0);
    for (int i = 0; i < n; ++i) {
      if (advance < 10) {
	if (univ[team[i].U-1] < 3) {
	  cout << team[i].I << endl;
	  ++univ[team[i].U-1];
	}
      } else if (advance < 20) {
	if (univ[team[i].U-1] < 2) {
	  cout << team[i].I << endl;
	  ++univ[team[i].U-1];
	}
      } else if (advance < 26) {
	if (univ[team[i].U-1] < 1) {
	  cout << team[i].I << endl;
	  ++univ[team[i].U-1];
	}
      }
    }

  }
  return 0;
}

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>(200000,false);
	count_t = vector<int>(200000,0);
	isDecided = vector<bool>(200000,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++: #include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
const int MAX = 1001;
typedef pair<int,int> QQ;
typedef pair<int,int> PP;
typedef pair<PP,QQ> P;

int main(){
  int n;

  while(cin >> n ,n){
    int id,uni,ac,pe;
    int tc[MAX]={0};
    vector<P> v;

    while(n--){
      cin >> id >> uni >> ac >> pe;
      v.push_back(P(PP(-ac,pe),QQ(id,uni)));
    } 
    sort(v.begin(),v.end());

    int cnt = 0;
    for(int i = 0; i < v.size() ; i++){
      int u = v[i].second.second;
      cnt++;
      if(cnt < 10){
	if(tc[u] < 3){
	  cout << v[i].second.first << endl;
	}
      }
      else if(cnt < 20){
	if(tc[u] < 2){
	  cout << v[i].second.first << endl;
	}
      }
      else if(cnt < 26){
	if(tc[u] < 1){
	  cout << v[i].second.first << endl;
	}
      }
      tc[u]++;
    } 
  }

  return 0;
}