#include<bits/stdc++.h>
using namespace std;
#define maxn 200050
#define ll long long
inline ll read(){
	ll h = 0,f = 1;
	char c = getchar();
	while(!(c >= '0' && c <= '9' || (c == '-'))){
		c = getchar();
	}
	while(c >= '0' && c <= '9' || (c == '-')){
		if(c == '-'){
			f = -1;
		}
		else{
			h = h*10+(c-'0');
		}
		c = getchar();
	}
	return h*f;
}
struct node{
	ll d;
	ll l;
	ll r;
	bool xing;
}shu[2*maxn];
bool cmp(node x,node y){
	//if(x.d == y.d)return y.xing;
	return x.d<y.d;
}
ll ans = 0,qian1 = 0,qian2 = 0,dang1 = 0,dang2 = 0,hou1 = 0,hou2 = 0;
void init(){
	memset(shu,0,sizeof(shu));
	ans = 0,qian1 = 0,qian2 = 0,dang1 = 0,dang2 = 0,hou1 = 0,hou2 = 0;
}
inline bool check(){
	if(dang2 == 0)return 0;
	if(qian2 + dang2 < hou1)return 0;
	if(hou2 + dang2 <= qian1)return 0;
	return 1;
}
int main(){
	freopen("lucky.in","r",stdin);
	freopen("lucky.out","w",stdout);
	int c,T;
	scanf("%d%d",&c,&T);
	while(T--){
		init();
		int n;
		scanf("%d",&n);
		for(int i = 1;i <= n;i++){
			ll l1,r1,l2,r2;
			int lin1 = i*2-1,lin2 = i*2;
			//scanf("%lld%lld%lld%lld",&l1,&r1,&l2,&r2);
			l1 = read(),r1 = read(),l2 = read(),r2 = read();
			shu[lin1].d = l2;
			shu[lin1].l = l1;
			shu[lin1].r = r1;
			shu[lin1].xing = 1;
			shu[lin2].d = r2+1;
			shu[lin2].l = l1;
			shu[lin2].r = r1;
			shu[lin2].xing = 0; 
			hou1 = hou1+l1;
			hou2 = hou2+r1;
		}
		sort(shu+1,shu+1+2*n,cmp);
		ll lin = 0;
		for(int i = 1;i <= 2*n;i++){
			if(check()){
				ans = ans+shu[i].d-lin;
			}
			lin = shu[i].d;
			if(shu[i].xing == 1){
				dang1 = dang1+shu[i].l;
				dang2 = dang2+shu[i].r;
				hou1 = hou1-shu[i].l;
				hou2 = hou2-shu[i].r;
			}
			else{
				dang1 = dang1-shu[i].l;
				dang2 = dang2-shu[i].r;
				qian1 = qian1+shu[i].l;
				qian2 = qian2+shu[i].r;
			}
		}
		printf("%lld\n",ans);
	}
	return 0;
}