#include<bits/stdc++.h>
#define rep(i,x,y) for(int i=x;i<=y;i++)
#define per(i,x,y) for(int i=x;i>=y;i--)
using namespace std;
const int N=6e6+10;
const int mod=998244353;
#define int long long
int qmi(int a,int b,int mod){//mod别弄错了
    int res=1;
    for(;b;b>>=1,a=a*a%mod)
        if(b&1)res=res*a%mod;
    return res;
}
void solve() {
    int n;cin>>n;
    vector<int>l(n+1),r(n+1);
    map<int,int>cnt;
    rep(i,1,n){
        cin>>l[i]>>r[i];
        cnt[l[i]]++,cnt[r[i]]+=0,cnt[r[i]+1]--;
    }
    int now=0;
    for(auto &[x,y]:cnt){
        now+=y;
        y=now;
    }
    int ans=0;
    rep(i,1,n){
        if(cnt[l[i]]==1 and cnt[r[i]]==1)ans++;
    }
    cout<<ans<<"\n";
}
signed main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    int tc = 1;
    cin >> tc;
    for (int i = 1; i <= tc; i++) {
        solve();
    }
}
//2
//3
//1 2
//3 4
//5 6
//3
//1 2
//2 3
//1 5