/*
    author: honglan0301
    2025.03.01
*/
#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define int long long
#define ll long long
#define ull unsigned long long
#define mod 998244353
#define endl "\n"
mt19937 rnd(time(0));
mt19937_64 rndl(time(0));

int cid,T,n,la[200005],lb[200005],ra[200005],rb[200005],cc[400005],cntc,sz[400005],ans,sumla,sumra;
int numrl[400005],numrr[400005],numll[400005],numlr[400005];
int ok1[400005],ok2[400005];

void init()
{
    for(int i=1;i<=cntc;i++) ok1[i]=0;
    for(int i=0;i<=cntc+1;i++) numrl[i]=numrr[i]=numll[i]=numlr[i]=0;
    cntc=0; ans=0; sumla=0; sumra=0;
}
void solve()
{
    for(int i=1;i<=n;i++) numrl[lb[i]]+=la[i],numrr[lb[i]]+=ra[i];
    for(int i=cntc;i>=1;i--) numrl[i]+=numrl[i+1],numrr[i]+=numrr[i+1];
    for(int i=1;i<=n;i++) numll[rb[i]]+=la[i],numlr[rb[i]]+=ra[i];
    for(int i=1;i<=cntc;i++) numll[i]+=numll[i-1],numlr[i]+=numlr[i-1];
    //solve1(); solve2(); solve3(); solve4();
}

int ck2(int x)
{
    int zzm=sumla+sumra-numrl[x+1]-numrr[x+1]-numll[x-1]-numlr[x-1];
    int lmn=numll[x-1],lmx=numll[x-1]+numlr[x-1];
    int rmn=numrl[x+1],rmx=numrl[x+1]+numrr[x+1];
    if(!zzm) return 0;
    if(zzm+lmx<rmn) return 0;
    if(lmn>=zzm+rmx) return 0;
    return 1;
}

signed main()
{
    cin.tie(0); cout.tie(0); ios::sync_with_stdio(0);
    freopen("lucky.in","r",stdin);
    freopen("lucky.out","w",stdout);
    cin>>cid>>T;
    while(T--)
    {
        init();
        cin>>n;
        for(int i=1;i<=n;i++) cin>>la[i]>>ra[i]>>lb[i]>>rb[i],ra[i]-=la[i],sumla+=la[i],sumra+=ra[i],cc[++cntc]=lb[i],cc[++cntc]=rb[i]+1;
        sort(cc+1,cc+cntc+1); cntc=unique(cc+1,cc+cntc+1)-cc-1;
        for(int i=1;i<=cntc;i++) sz[i]=cc[i+1]-cc[i];
        for(int i=1;i<=n;i++) lb[i]=lower_bound(cc+1,cc+cntc+1,lb[i])-cc,rb[i]=upper_bound(cc+1,cc+cntc+1,rb[i])-cc-1;
        for(int i=1;i<=n;i++) ok1[lb[i]]++,ok1[rb[i]+1]--;
        for(int i=1;i<=cntc;i++) ok1[i]+=ok1[i-1];
        solve();
        for(int i=1;i<=cntc;i++) ok2[i]=ck2(i);
        for(int i=1;i<=cntc;i++) if(ok1[i]&&ok2[i]) ans+=sz[i];
        cout<<ans<<endl;
    }
}