func_code_string: #include <bits/stdc++.h>   using namespace std;   bool sort_d(long long x, long long y) { return x > y; }   int gcd(long long x, long long y) {     if (!y)       return x;     else       return gcd(y, x % y);   }   int lcm(long long x, long long y) { return (x * y) / gcd(x, y); }   int main() {     int n, m, a, b;     std::vector<int> Cs, Ce, Ps, Pe;     cin >> n;     for (int i = 0; i < n; i++) {       cin >> a >> b;       Cs.push_back(a);       Ce.push_back(b);     }     cin >> m;     for (int i = 0; i < m; i++) {       cin >> a >> b;       Ps.push_back(a);       Pe.push_back(b);     }     sort(Cs.begin(), Cs.end());     sort(Ce.begin(), Ce.end());     sort(Ps.begin(), Ps.end());     sort(Pe.begin(), Pe.end());     a = max(Ps[Ps.size() - 1] - Ce[0], 0);     b = max(Cs[Cs.size() - 1] - Pe[0], 0);     cout << max(a, b) << endl;     return 0;   }   