#include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n >> m;     pair<int, int> cc[105];     for (int i = 1; i <= m; i++) {       int a, b, c, d;       cin >> a >> b >> c >> d;       for (int j = a; j <= b; j++) {         if (!cc[j].first || c < cc[j].first) {           cc[j].first = c;           cc[j].second = d;         }       }     }     int ans = 0;     for (int i = 1; i <= n; i++) ans += cc[i].second;     cout << ans;   }   