#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <cstring>
#include <vector>
#include <queue>
#include <string>
#include <set>
using namespace std;
typedef long long ll;
ll t,n,m,ans,num,x,y,p,k,cnt;
int main()
{
    scanf("%lld",&t);
    while(t--)
    {
        cnt=0;
        num=0;
        scanf("%lld",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%lld %lld",&x,&y);
            if(x==1)
            {
                if(y>num)
                    num=y;
            }
            else
            {
                if(y>cnt)
                    cnt=y;
            }
        }
        if(n==0)
            cout<<0<<endl;
        else if(n==1)
            if(x==1)
                cout<<y+1<<endl;
            else
                cout<<y+2<<endl;
        else if(num>cnt)
            if(num-cnt==1)
                cout<<num+2<<endl;
            else
                cout<<num+1<<endl;
        else if(num==cnt)
            cout<<num+2<<endl;
        else if(num<cnt)
            cout<<cnt+2<<endl;
    }
}