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

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        vector<pair<int,int>>a(n);
        for(int i = 0; i<n; i++){
            cin >> a[i].first >> a[i].second;
        }
        sort(a.begin(),a.end());
        int cur = 1;
        int r = 0;
        priority_queue<int,vector<int>,greater<int>>pq;
        int ans = 0;
        while(pq.size() || r < n){
            while(pq.size() && pq.top() < cur){
                pq.pop();
            }
            while(r<n && a[r].first == cur){
                pq.push(a[r].second);
                r++;
            }
            if(pq.size() == 0 && r < n){
                cur = a[r].first;
                while(r<n && a[r].first == cur){
                    pq.push(a[r].second);
                    r++;
                }
            }
            if(pq.size()){
                pq.pop();
                ans++;
            }
            cur++;
        }
        cout << ans << '\n';
    }
    return 0;
}