#include <bits/stdc++.h>   using namespace std;   inline bool equal(double _x, double _y) {     return _x > _y - 1e-9 && _x < _y + 1e-9;   }   int l[105], r[105], t[105], c[105], ans, mx, id;   int main() {     int n, m;     scanf( %d%d , &n, &m);     for (int i = 0; i < m; i++) scanf( %d%d%d%d , &l[i], &r[i], &t[i], &c[i]);     for (int j = 1; j <= n; j++) {       mx = 1e9;       id = -1;       for (int i = 0; i < m; i++) {         if (l[i] <= j && j <= r[i] && t[i] < mx) {           mx = t[i];           id = i;         }       }       if (~id) ans += c[id];     }     printf( %d n , ans);   }   