Go: // A Way to Invite Friends(友だちの誘い方)
// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2331&lang=ja
package main

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

const N_MAX = 1000001

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n := nextInt(sc)
	allow_list := make([]int, N_MAX+100)
	nMax := 0

	for i := 0; i < n; i++ {
		a, b := nextInt(sc), nextInt(sc)
		allow_list[a] += 1
		allow_list[b+1] += -1
		nMax = int(math.Max(float64(nMax), float64(b)))
	}

	for i := 2; i <= N_MAX; i++ {
		allow_list[i] += allow_list[i-1]
	}

	res := 0
	for i := 2; i <= nMax; i++ {
		if i-1 <= allow_list[i] { // i人誘う時に行きたい人の人数を超えないか(自分を含めて)
			res = i - 1 // 自分は除く
		}
	}

	fmt.Println(res)
}

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, err := strconv.Atoi(sc.Text())
	if err != nil {
		panic(err)
	}
	return i
}

C++: #include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>

using namespace std;
#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for(int (i) = (a) - 1; (i) >= 0; (i)--)
#define FORR(i, a, b) for(int (i) = (a) - 1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template<typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

void solve(int N) {
    VI seg(100010, 0);
    REP(i, N) {
        int a, b;
        scanf("%d%d", &a, &b);
        seg[a]++;
        seg[b + 1]--;
    }
    REP(i, 100008) seg[i + 1] += seg[i];
    int ans = 0;
    FOR(i, 1, N + 2) {
        //cout << seg[i] << " ";
        if (seg[i] >= i - 1) ans = i - 1;
    } 
    cout << ans << endl;
    return;
}

signed main(void) {
    LL n, m, p, a, b, c, x, y, z, q;
    string s;
    bool f = false;
    while (cin >> n, n) {
        solve(n);
        return 0;
    }
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on

void solve() {
  int n;
  cin >> n;
  vi t(100002);
  while (n--) {
    int a, b;
    cin >> a >> b;
    t[a]++;
    t[b + 1]--;
  }
  loop(i, 1, t.size()) t[i] += t[i - 1];
  int c = 0;
  loop(i, 1, t.size()) if (t[i] >= i - 1) c = i - 1;
  cout << c << endl;
}

C++: #include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <climits>

using namespace std;

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();}

typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n) FOR(i,0,n-1)

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

int main() {
	int n;
	vi num(100002, 0);

	cin >> n;

	int a, b;

	REP(i, n) {
		cin >> a >> b;

		FOR(j, a-1, b-1) {
			num[j]++;
		}
	}

	int ans = 0;
	FOR(i, 1, n) {
		if(i <= num[i]) {
			ans = i;
		}
	}

	cout << ans << endl;

	return 0;
}

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

int main(){
  int n;
  cin>>n;
  vector<int> a(n);
  vector<int> b(n);
  for(int i=0;i<n;i++){
    cin>>a[i]>>b[i];
  }

  vector<int> join=a;
  sort(join.begin(),join.end());
  vector<int> leave=b;
  sort(leave.begin(),leave.end());
  int joinde=0;
  int leinde=0;
  int mem=1;
  int res=0;
  for(int i=2;i<=n+1;i++){
    
    while(joinde<n && join[joinde]==i){
      mem++;
      joinde++;
    }
    while(leinde<n && leave[leinde]<i){

      mem--;
      leinde++;
    }

    if(i<=mem){
      res=max(res,i-1);
    }
    
  }
  cout<<res<<endl;
  return 0;

}

C++: #define _USE_MATH_DEFINES
#include <bits/stdc++.h>
// #define USE_LLONG_AS_INT
#ifdef USE_LLONG_AS_INT
#define int long long
#define inf (1ll<<60)
#else
#define inf (1<<30)
#endif
#define rep(i,n) for(int i=0;i<n;i++)
#define Rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a,b) for(int i=a;i<=b;i++)
#define rev(i,n) for(int i=(n)-1;i>=0;i--)
#define vi vector<int>
#define vvi vector<vi>
#define pb push_back
#define pi pair<int,int>
#define vp vector<pair<int,int>>
#define mp make_pair
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define MEMSET(a) memset(a,0,sizeof(a))
#define Yes(f) cout<<(f?"Yes":"No")<<endl
#define yes(f) cout<<(f?"yes":"no")<<endl
#define YES(f) cout<<(f?"YES":"NO")<<endl
#define SORT(v) sort(all(v))
#define RSORT(v) sort(all(v), greater<int>())

using namespace std;

const int mod=1e9+7;
const string sp=" ";

void run();

void init() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(12);
}

signed main(){
    init();
    run();
    return 0;
}

int f[100010];

void run(){
    int n;
    cin>>n;
    rep(i,n){
        int a,b;
        cin>>a>>b;
        f[a]++,f[b+1]--;
    }
    int ans=0;
    Rep(i,1,100010){
        f[i]+=f[i-1];
        if(f[i]>=i-1)ans=i-1;
    }
    cout<<ans<<endl;
}