#include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n >> m;     vector<int> start(m);     vector<int> ending(m);     vector<int> time(m);     vector<int> prize(m);     int money = 0;     for (int i = 0; i < m; i++) {       cin >> start[i] >> ending[i] >> time[i] >> prize[i];     }     int mn = 9000;     int currprize;     for (int j = 1; j <= n; j++) {       mn = 9000;       currprize = 0;       for (int i = 0; i < m; i++) {         if (start[i] <= j && ending[i] >= j && time[i] < mn) {           mn = time[i];           currprize = prize[i];         }       }       money += currprize;     }     cout << money << endl;   }   