func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int ESP = 1e18;   long long int FCB = 1e9 + 7;   long long int dir[][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};   const long long int N = 5005;   long long int l[N], r[N];   vector<pair<long long int, long long int>> vv;   bool fly(long long int x, long long int y) {     if (l[x] >= r[y]) return false;     if (r[x] <= l[y]) return false;     return true;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     ;     long long int n;     cin >> n;     for (long long int i = 1; i < n + 1; i++) cin >> l[i] >> r[i];     for (long long int i = 1; i < n + 1; i++) {       for (long long int j = 1; j < n + 1; j++) {         if (i != j && fly(i, j)) vv.push_back(make_pair(i, j));       }     }     map<long long int, long long int> mp;     long long int zz = vv.size();     for (long long int i = 0; i < zz; i++) {       mp[vv[i].first]++;       mp[vv[i].second]++;     }     vector<long long int> ans;     for (long long int i = 1; i <= n; i++) {       if (mp[i] == zz) ans.push_back(i);     }     long long int dd = ans.size();     cout << dd <<   n ;     for (long long int i = 0; i < dd; i++) cout << ans[i] <<    ;     cout <<   n ;     return 0;   }   