#include <bits/stdc++.h>
#define ioclear std::ios::sync_with_stdio(false);std::cin.tie(nullptr);std::cout.tie(nullptr);
#define endl '\n'
#define int long long 

using namespace std;

using pii = std::pair<int, int>;

void solve()
{
	int n;
	std::cin >> n;
	std::vector<pii> p(n + 1);
	for(int i = 1; i <= n; i++)
		std::cin >> p[i].first >> p[i].second;
	std::sort(p.begin() + 1, p.end());
	std::priority_queue<int, std::vector<int>, std::greater<int>> pq;
	int x = 1, cur = 1, ans = 0;
	while(1)
	{
		while(pq.size() && pq.top() < x)
			pq.pop();
		if(pq.empty())
		{
			if(cur > n)
				break;
			x = p[cur].first;	
		}
		else
		{
			ans++;
			pq.pop();
			x++;
		}
		while(cur <= n && p[cur].first <= x)
		{
			pq.push(p[cur].second);
			cur++;
		}
	}
	std::cout << ans << endl;
}

signed main()
{
	#ifdef ONLINE_JUDGE
	ioclear;
	#endif
	int t;
	std::cin >> t;
	while(t--)
		solve();
}