#include<bits/stdc++.h>
using namespace std;
int goal=1;
int n,m;
int T;
int book[500005];
signed main2()
{
	goal=1;
	bool flag=1;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	{
	    book[i]=0;
	}
	for(int i=1;i<=m;i++)
	{
		int opt,x;
		cin>>opt>>x;
		if(flag)
		{
    		if(opt==2)
    		{
    			goal--;
    			book[x]--;
    		}
    		if(opt==1) book[x]++;
    		bool flg=1;
    		for(int i=1;i<=n;i++)
    		{
    		    if(book[i]<goal)
    		    {
    		        flg=0;
    		        break;
    		    }
    		}
    		if(flg)
    		{
    		    cout<<i<<"\n";
    		    flag=0;
    		}
		}
		
	}
	cout<<"-1\n";
	return(0);
}
signed main()
{
	cin>>T;
	while(T--)
	{
		main2();
	}
	return(0);
}