func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int p, q, l, r;     cin >> p >> q >> l >> r;     vector<pair<int, int> > z_timing, x_timing;     int start, stop;     for (int i = 0; i < p; i++) {       cin >> start >> stop;       z_timing.push_back(make_pair(start, stop));     }     for (int i = 0; i < q; i++) {       cin >> start >> stop;       x_timing.push_back(make_pair(start, stop));     }     int answer = 0;     for (int i = l; i <= r; i++) {       for (int j = 0; j < q; j++) {         bool has_intersected = false;         start = x_timing[j].first + i;         stop = x_timing[j].second + i;         for (int k = 0; k < p; k++) {           if (start <= z_timing[k].second && stop >= z_timing[k].first) {             answer++;             has_intersected = true;             break;           }         }         if (has_intersected == true) {           break;         }       }     }     cout << answer;     return 0;   }   