func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 25;   int main() {     int n, m, l, r, t, c;     cin >> n >> m;     pair<int, int> s[n + 1];     for (int i = (1), _b = (n + 1); i < (_b); ++i) s[i] = make_pair(0, 0);     for (int i = (0), _b = (m); i < (_b); ++i) {       cin >> l >> r >> t >> c;       for (int j = (l), _b = (r + 1); j < (_b); ++j) {         if (!s[j].second)           s[j] = make_pair(t, c);         else {           if (t < s[j].first) {             s[j] = make_pair(t, c);           }         }       }     }     int ret = 0;     for (int i = (1), _b = (n + 1); i < (_b); ++i) {       ret += s[i].second;     }     cout << ret << endl;     return 0;   }   