#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

const int N = 1e5 + 10;
const ll INF = 1e9;

pll lr[N];

ll calc(ll l1, ll r1, ll l2, ll r2)
{
	if (r1 < l2)
	{
		return 1ll * (r1 - l1 + 1) * (r2 - l2 + 1);
	}
	else
	{
		r1 = min(r1, r2);
		l2 = max(l2, l1);
		return 1ll * (l2 - l1) * (r2 - l2 + 1) + 1ll * (r1 - l2 + 1) * (r2 - l2 + r2 - r1) / 2;
	}
}

int main()
{
	ios::sync_with_stdio(false);
	int t, pos1, pos2;
	ll minl, maxr;
	bool samepos;
	cin >> t;
	while (t--)
	{
		int n;
		cin >> n;
		for (int i = 1; i <= n; i++)
			cin >> lr[i].first >> lr[i].second;
		if (n == 1)
		{
			cout << 1 << endl;
			continue;
		}
		samepos = false;
		minl = INF, maxr = -INF;
		pos1 = pos2 = 0;
		for (int i = 1; i <= n; i++)
		{
			if (lr[i].first < minl && lr[i].second > maxr)
			{
				pos1 = i, minl = lr[i].first;
				pos2 = i, maxr = lr[i].second;
			}
			else
			{
				if (lr[i].first < minl)
				{
					pos1 = i;
					minl = lr[i].first;
				}
				else if (lr[i].second > maxr)
				{
					pos2 = i;
					maxr = lr[i].second;
				}
			}
		}
		if (pos1 == pos2)
		{
			samepos = true;
			swap(lr[1], lr[pos1]);
		}
		else
		{
			if (pos2 == 1 && pos1 == 2)
				swap(lr[1], lr[2]);
			else if (pos2 == 1)
			{
				swap(lr[1], lr[2]);
				swap(lr[pos1], lr[1]);
			}
			else
			{
				swap(lr[1], lr[pos1]);
				swap(lr[2], lr[pos2]);
			}
		}
		if (n == 2 && !samepos)
		{
			cout << calc(lr[1].first, lr[1].second, lr[2].first, lr[2].second) << endl;
			continue;
		}
		ll secl = 1e9, secr = -1e9;
		int st = (samepos ? 2 : 3);
		for (int i = st; i <= n; i++)
		{
			secl = min(secl, lr[i].first);
			secr = max(secr, lr[i].second);
		}
		ll p1 = calc(minl, maxr, secl, secr) + calc(secl, secr, minl, maxr) - calc(secl, secr, secl, secr);
		if (samepos)
		{
			cout << p1 << endl;
		}
		else
		{
			p1 += calc(minl, secl - 1, lr[2].first, secl - 1);
			p1 += calc(secr + 1, lr[1].second, secr + 1, maxr);
			if (n >= 4)
				p1 += calc(minl, secl - 1, secr + 1, maxr);
			else
			{
				if (lr[1].second >= secl - 1 || lr[2].first <= secr + 1)
					p1 += calc(minl, secl - 1, secr + 1, maxr);
				else
					p1 += calc(minl, secl - 1, lr[2].first, maxr) + calc(minl, lr[1].second, secr + 1, maxr) - calc(minl, lr[1].second, lr[2].first, maxr);
			}
			cout << p1 << endl;
		}
	}
}