func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long int n;     cin >> n;     long long int max1 = 0, max2 = 0, min1 = (1000000000 + 9),                   min2 = (1000000000 + 9);     for (int i = 0; i < n; i++) {       long long int x, y;       cin >> x >> y;       if (y < min1) {         min1 = y;       }       if (x > max1) {         max1 = x;       }     }     long long int m;     cin >> m;     for (int i = 0; i < m; i++) {       long long int x, y;       cin >> x >> y;       if (y < min2) {         min2 = y;       }       if (x > max2) {         max2 = x;       }     }     long long int x1 = (max1 - min2);     long long int x2 = (max2 - min1);     long long int x3 = max(x1, x2);     if (x3 < 0) {       cout << 0 << endl;     } else {       cout << x3 << endl;     }   }   