#include<bits/stdc++.h>
#define ll long long
#define all(x) x.begin(), x.end()
#define lowbit(i) ((i)&(-i))
#define pii pair<int,int>
#define endl '\n'
#define mk(x,y) make_pair(x,y)
#define popcount(x) __builtin_popcount(x)
const double pi=3.14159265358979323846;
const double eps=1e-9;
const int inf=1e9;
const long long INF=4e18;
const int mod=1e9+7;
using namespace std;
const int N=1e5+10;

void solve()
{
    int n;
    cin>>n;
    vector<array<int,2>>a(n+1);
    for(int i=1;i<=n;i++){
        cin>>a[i][0]>>a[i][1];
    }
    sort(a.begin()+1,a.end());
    int ans=0;
    priority_queue<int,vector<int>,greater<int>>q;
    int l=-1,nxt=1;
    while(1){
        while(q.size()&&q.top()<l)q.pop();
        if(q.empty()){
            if(nxt>n)break;
            l=a[nxt][0];
        }
        else{
            ans++;
            q.pop();
            l++;
        }
        while(nxt<=n&&a[nxt][0]<=l){
            q.push(a[nxt][1]);
            nxt++;
        }
    }
    cout<<ans<<endl;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    
    int T=1;
    cin>>T;
    while(T--){
        solve();
    }
    return 0;
}