func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 200005;   bool r[MAXN];   int main() {     int n;     vector<pair<int, pair<int, int>>> v;     cin >> n;     for (int i = 0; i < n; ++i) {       int l, r;       cin >> l >> r;       v.emplace_back(l, make_pair(1, i));       v.emplace_back(r + 1, make_pair(0, i));     }     sort(v.begin(), v.end());     set<int> s;     for (int i = 0; i < v.size(); ++i) {       while (i < v.size()) {         if (v[i].second.first == 1) s.insert(v[i].second.second);         if (v[i].second.first == 0) s.erase(s.find(v[i].second.second));         if (v[i].first == v[i + 1].first)           i++;         else           break;       }       if (s.size() == 1) r[*s.begin()] = 1;     }     for (int i = 0; i < n; ++i) {       if (r[i] == 0) {         cout << i + 1 << endl;         return 0;       }     }     cout << -1 << endl;     return 0;   }   