func_code_string: #include <bits/stdc++.h>   int main() {     int p, q, l, r;     scanf( %d %d %d %d , &p, &q, &l, &r);     std::vector<std::pair<int, int> > fixed;     std::vector<std::pair<int, int> > changing;     for (int k = 0; k < p; k++) {       int a, b;       scanf( %d %d , &a, &b);       fixed.push_back(std::pair<int, int>(a, b));     }     for (int k = 0; k < q; k++) {       int a, b;       scanf( %d %d , &a, &b);       changing.push_back(std::pair<int, int>(a, b));     }     bool done;     int output(0);     for (int k = l; k <= r; k++) {       done = 0;       for (int x = 0; x < fixed.size(); x++) {         if (done) {           continue;         }         for (int y = 0; y < changing.size(); y++) {           if ((fixed[x].second < k + changing[y].first) ||               (k + changing[y].second < fixed[x].first)) {             continue;           } else {             done = 1;             ++output;             break;           }         }       }     }     printf( %d n , output);     return 0;   }   