#include<bits/stdc++.h>
#define AC return 0;
#define int long long 
#define pii pair<int,int>
#define all(tar) tar.begin(),tar.end()
const int maxx=2e5+5;
const int mod=998244353; 
using namespace std;
int n,m,t;

struct Line {
    int l, r;
    bool operator < (const Line &other) const {
        if (r != other.r)
            return r < other.r;
        return l < other.l;
    }
};

void Solve()
{
    int n;
    cin >> n;
    vector < Line > a(n + 1);
    vector<int>num;
    map<int,vector<int>>mp;
    for (int i = 1; i <= n; i++)
        cin >> a[i].l >> a[i].r;
    for(int i=1;i<=n;i++){
        mp[a[i].l].push_back(a[i].r);
        num.push_back(a[i].l);
    }
    num.push_back(1e18);
    sort(all(num));
    int ans=0;
    num.erase(unique(all(num)),num.end());
    sort (a.begin() + 1, a.end());
    int x=num[0];
    priority_queue<int,vector<int>,greater<int>>q;
    for(int i=0;i<(int)num.size()-1;i++){
        int l=num[i];
        for(auto x:mp[num[i]]){
            q.push(x);
        }
        while(l<num[i+1]){
            if(!q.empty()&&q.top()>=l)ans++,q.pop(),++l;
            else {
                while(!q.empty())q.pop();
                break;
            }
        }
    }
    cout<<ans<<'\n';
}

signed main(){
   ios::sync_with_stdio(false);
   cin.tie(0);
   cout.tie(0);

    int T = 1;
    cin >> T;

    while (T--)
    {
        Solve();
    }

   AC
}