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

const int N = 1e5 + 100;
int n, L[N], R[N];
int ls[N], rs[N];
int zt[N], f[105];

bool cmp(int x, int y) {
    return x > y;
}

int work(int l1, int r1, int l2, int r2) {
    if(l1>l2)swap(l1,l2),swap(r1,r2);
    int res=0;
    res=res+(l2-l1)*(r2-l2+1);
    if(r2<r1)r1=r2;
    else res=res+(r2-r1)*(r1-l2+1);
    //cout<<res<<" "<<r1<<" "<<l2<<endl;
    if(r1<=l2)return res;
    res=res+(r1-l2)*(r1-l2+1)/2;
    return res;
}
int ans;
void slove() {
    scanf("%lld", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%lld %lld", &L[i], &R[i]);
        ls[i] = L[i]; rs[i] = R[i];
    }
    if(n==1){
        puts("1");return;
    }
    sort(ls + 1, ls + n + 1);
    sort(rs + 1, rs + n + 1, cmp);
    int l1 = ls[1], l2 = ls[2], r1 = rs[1], r2 = rs[2];
    for (int i = 1; i <= n; i++) {
        zt[i] = 0;
        if (l1 == L[i]) zt[i] |= 1;
        if (l2 == L[i]) zt[i] |= 2;
        if (r1 == R[i]) zt[i] |= 4;
        if (r2 == R[i]) zt[i] |= 8;
    }

    for (int i = 0; i < 50; i++) f[i] = 0;
    f[0] = 1;
    for (int i = 1; i <= n; i++) {
        for (int j = 15; j >= 0; j--)
            for (int k = 0; k < 4; k++)
                if (!((j >> k) & 1) && ((zt[i] >> k) & 1))
                    f[j | (1 << k)] = 1;
    }
    ans=0;
    if (f[15]) {
        ans =  work(l1, r2, l2, r1) ;
        //cout<<work(l1,r1,l2,r2)<<" "<<work(l1, r2, l2, r1) <<" "<< work(l2, r2, l2, r2)<<endl;;
    }
    else {
        for (int i = 1; i <= n; i++) {
            if (((zt[i] >> 0) & 1) && ((zt[i] >> 2) & 1)) {
                ans =max(ans,work(l1, r1, l2, r2)); 
                //break;
            }
            if (((zt[i] >> 0) & 1) && ((zt[i] >> 3) & 1)) {
                ans =max(ans,work(l1, r2, l2, r1)) ;
                //break;
            }
            if (((zt[i] >> 1) & 1) && ((zt[i] >> 2) & 1)) {
                ans =max(ans, work(l2, r1, l1, r2));
                //break;
            }
            if (((zt[i] >> 1) & 1) && ((zt[i] >> 3) & 1)) {
                ans =max(ans, work(l2, r2, l1, r1));
                //break;
            }
        }
    }
    printf("%lld\n", ans);
}

signed main() {
   // cout<<work(1,4,2,5)<<endl;
   // return 0;
    int t; scanf("%lld", &t);
    
    while (t--) slove();
    return 0;
}