func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     int m;     cin >> n >> m;     bool ans[m + 1];     for (int i = 0; i <= m; i++) {       ans[i] = false;     }     int a[n];     vector<pair<int, int> > v;     for (int i = 0; i < n; i++) {       int a;       int b;       cin >> a;       cin >> b;       v.push_back(make_pair(a, b));     }     for (int i = 0; i < n; i++) {       int start = v[i].first;       int end = v[i].second;       for (int j = start; j <= end; j++) {         if (ans[j] == false) ans[j] = true;       }     }     vector<int> final;     int result = 0;     for (int i = 1; i <= m; i++) {       if (ans[i] == false) {         final.push_back(i);         result++;       }     }     cout << result << endl;     for (int i = 0; i < final.size(); i++) {       cout << final[i] <<    ;     }   }   