#include <bits/stdc++.h>
#define int long long
using namespace std;

const int N = 2e5 + 5;

#define pii pair < int, int > 
#define fi first
#define se second

struct node {
    pii a, b;
}p[N];

int calc ( int l, int r, int L, int R ) {
    l = max ( L, l );
    r = min ( r, R );
    if ( l > r ) return 0;
    return r - l + 1;
}

signed main ( ) {
    freopen ( "lucky.in", "r", stdin );
    freopen ( "lucky.out", "w", stdout );
    int Idc, T; cin >> Idc >> T;
    while ( T -- ) {
        int n, sum = 0; cin >> n;
        for ( int i = 1; i <= n; i ++ ) {
            int l, r; cin >> l >> r; sum += l;
            p[i].b = { l, r };
            cin >> l >> r; 
            p[i].a = { l, r };
        }
        sort ( p + 1, p + n + 1, [ ] ( node x, node y ) { return x.a.fi < y.a.fi; } );
        int L = 0, cnt = 0, sm = sum, R = 0;
        // cout << "calc\n";
        for ( int i = 1; i <= n; i ++ ) {
            cnt += p[i].b.se; sm -= p[i].b.fi;
            // cout << cnt << " " << sm << "\n";
            if ( cnt >= sm ) { 
                L = p[i].a.fi;
                break;
            }
        }
        sort ( p + 1, p + n + 1, [ ] ( node x, node y ) { return x.a.se > y.a.se; } );
        sm = sum; cnt = 0;
        for ( int i = 1; i <= n; i ++ ) {
            cnt += p[i].b.se; sm -= p[i].b.fi;
            if ( cnt > sm ) {
                R = p[i].a.se;
                break;
            }
        }
        if ( L > R ) { cout << 0 << "\n"; continue; }
        sort ( p + 1, p + n + 1, [ ] ( node x, node y ) { return x.a.fi < y.a.fi; } );
        int d = 0, del = 0;
        for ( int i = 1; i <= n; i ++ ) {
            if ( d < p[i].a.fi ) del += calc ( d + 1, p[i].a.fi - 1, L, R ); 
            d = max ( d, p[i].a.se );
        }
        // cout << L << " " << R << "\n";
        cout << R - L + 1 - del << "\n";
    }
}
/*
0 4
2
1 2 1 1
1 1 2 2
2
1 1 1 2
1 1 2 3
2
1 2 1 2
2 3 3 4
4
1 2 1 4
3 4 1 2
3 4 2 3
3 4 3 4

0 1 
2
1 1 1 2
1 1 2 3

*/