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;
using LL = long long;
using ULL = unsigned long long;
const double PI = acos(-1);
template<class T>constexpr T INF() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T HINF() { return INF<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); };
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); };
template<typename T>vector<T> make_v(size_t a){ return vector<T>(a); }
template<typename T,typename... Ts>auto make_v(size_t a, Ts... ts){ return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template<typename T,typename V>typename enable_if<is_class<T>::value==0>::type fill_v(T &t, const V &v){ t = v; }
template<typename T,typename V>typename enable_if<is_class<T>::value!=0>::type fill_v(T &t, const V &v){ for(auto &e : t) fill_v(e, v); }
const int vy[] = { -1, -1, -1, 0, 1, 1, 1, 0 }, vx[] = { -1, 0, 1, 1, 1, 0, -1, -1 };
const int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(LL n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(LL n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
LL gcd(LL a, LL b) { if (b == 0)return a; return gcd(b, a%b); };
LL lcm(LL a, LL b) { LL g = gcd(a, b); return a / g*b; };
# define ALL(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        sort(ALL((wpwpw)));(wpwpw).erase(unique(ALL((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(ALL((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(ALL((rprpr)),(rprpr).begin(),TU<char>)
# define FOR(i,tptpt,ypypy)   for(LL i=(tptpt);i<(ypypy);i++)
# define REP(i,upupu)         FOR(i,0,upupu)
# define INIT                 std::ios::sync_with_stdio(false);std::cin.tie(0)

int n;
int I[303], U[303], A[303], P[303];
int shozo[303];

int main(){
    while(cin >> n && n){
        REP(i, 303)shozo[i] = 0;
        vector<pair<pair<int, int>, pair<int, int>>> v;
        REP(i, n){
            cin >> I[i] >> U[i] >> A[i] >> P[i];
            v.emplace_back(make_pair(make_pair(-A[i], P[i]), make_pair(I[i], i)));
        }
        sort(ALL(v));
        int idx = 0;
        REP(i, n){
            int team = v[i].second.second;
            if(idx < 10){
                if(shozo[U[team]] < 3){
                    cout << I[team] << endl;
                    shozo[U[team]]++;
                    idx++;
                }
            }else if(idx < 20){
                if(shozo[U[team]] < 2){
                    cout << I[team] << endl;
                    shozo[U[team]]++;
                    idx++;
                }
            }else if(idx < 26){
                if(shozo[U[team]] < 1){
                    cout << I[team] << endl;
                    shozo[U[team]]++;
                    idx++;
                }
            }
        }
    }
}

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,false);
	count_t = vector<int>(n,0);
	isDecided = vector<bool>(n,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;
}