#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2e5 + 5;
int c, T;
int n;
struct dat {
    int l1, r1, l2, r2;
} a[N];
int b[N << 1];
vector<int> st[N << 1], ed[N << 1];
signed main() {
    freopen("lucky.in", "r", stdin);
    freopen("lucky.out", "w", stdout);
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    cin >> c >> T;
    while (T--) {
        cin >> n;
        int pre1 = 0, pre2 = 0, now = 0, suf1 = 0, suf2 = 0;
        for (int i = 1, l1, r1, l2, r2; i <= n; i++) {
            cin >> l1 >> r1 >> l2 >> r2;
            suf1 += l1, suf2 += r1;
            a[i] = {l1, r1, l2, r2 + 1};
            b[i] = l2, b[i + n] = r2 + 1;
        }
        sort(b + 1, b + 2 * n + 1);
        int t = unique(b + 1, b + 2 * n + 1) - (b + 1);
        for (int i = 1; i <= n; i++) {
            a[i].l2 = lower_bound(b + 1, b + t + 1, a[i].l2) - b;
            a[i].r2 = lower_bound(b + 1, b + t + 1, a[i].r2) - b;
            st[a[i].l2].push_back(i);
            ed[a[i].r2].push_back(i);
        }
        int ans = 0;
      //  cout << 48670672 + 602959541 - 288854721 << endl;
        for (int i = 1; i < t; i++) {
            for (int x : ed[i]) {
                pre1 += a[x].l1;
                pre2 += a[x].r1;
                now -= a[x].r1;
            }
            for (int x : st[i]) {
                suf1 -= a[x].l1;
                suf2 -= a[x].r1;
                now += a[x].r1;
            }
        //    cout << pre1 << " " << pre2 << " " << now << " " << suf1 << " " << suf2 << endl;
            if (!now) continue;
            int m = (pre1 + now + suf1 + 1) / 2;
            if (m > pre1 && m <= pre1 + now) {
                ans += b[i + 1] - b[i];
                //cout << now << " " << ans << endl;
                continue;
            }
            else if (m <= pre1) {
                m = (pre1 + now + suf2 + 1) / 2;
                if (m > pre1) {
                    ans += b[i + 1] - b[i];
                  //  cout << now << " " << ans << endl;
                    continue;
                }
            }
            else if (m > pre1 + now) {
                m = (pre2 + now + suf1 + 1) / 2;
                if (m <= pre2 + now) {
                    ans += b[i + 1] - b[i];
                 //   cout << now << " " << ans << endl;
                    continue;
                }
            }
        }
        cout << ans << '\n';
        for (int i = 1; i <= t; i++)
            st[i].clear(), ed[i].clear();
    }
    return 0;
}