func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     int n;     long long int k;     cin >> n >> k;     vector<pair<int, int> > a(n);     for (int i = 0; i < n; i++) {       cin >> a[i].first >> a[i].second;     }     sort(a.begin(), a.end());     int ans = -1;     long long int l = 0, r = 2e9;     for (int i = 0; i < 60; i++) {       long long int m = l + (r - l) / 2;       int less = 0, right = 0, center = 0;       long long int money = 0;       vector<int> c;       for (auto &e : a) {         if (e.second < m) {           money += e.first;         } else if (e.first >= m) {           money += e.first;           right++;         } else if (e.first < m && m <= e.second) {           c.push_back(e.first);         }       }       int need = max(0, (n + 1) / 2 - right);       if (need > c.size()) {         r = m - 1;       } else {         for (int i = 0; i < c.size(); i++) {           if (i < c.size() - need)             money += c[i];           else             money += m;         }         if (money <= k) {           ans = m;           l = m + 1;         } else {           r = m - 1;         }       }     }     cout << ans <<   n ;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int t;     cin >> t;     while (t--) {       solve();     }     return 0;   }   