#include<bits/stdc++.h>
#define ios ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
using namespace std;using ll = long long;using PLL = pair<ll,ll>;
const ll MAX = 1e18;const ll MIN = -1e18;const ll INF=0x3f3f3f3f;
const ll Q = 2e5+9;const ll MOD = 1e9 + 7;
vector<pair<ll,ll>> v;
bool cmp(pair<ll,ll> l,pair<ll,ll> r){
    if(l.first==r.first) return l.second<r.second;
    return l.first<r.first;
}
void solve(){
    v.clear();
   ll n;cin>>n;
   for (ll i = 0; i < n; i++)
   {
    ll o,p;cin>>o>>p;
    v.push_back({o,p});
   }
   ll cnt=-1;ll ans=0;
   sort(v.begin(),v.end(),cmp);
   for (ll i = 0; i < n; i++)
   {
        if(v[i].first>=cnt){
            cnt=v[i].first+1;
            ans++;
        }else {
            if(v[i].second>=cnt) cnt++,ans++;
        }
   }
   
   cout<<ans<<"\n";
}
int main(){
    ios;ll _=1;cin>>_;
    while (_--)solve();
    return 0;
}