#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
#define F(N,S,T) for(int N=(S);N<=(T);N++)

const int N=1001001;
int x[N],y[N];
typedef pair<int,int> P;

void work(){
    int n;
    cin>>n;
    F(i,1,n)cin>>x[i]>>y[i];
    set<P> s;
    F(i,1,n)s.insert(P(x[i],y[i]));
    int ans=0;
    F(i,1,n)ans=max(ans,(x[i]==2&&s.count(P(1,y[i]+1))?1:0)+x[i]+y[i]);
    cout<<ans<<endl;
}

int main(){
    ios::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--){
        work();
    }
    return 0;
}