#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
	ll n,m;
	ll a[100005];
	int T;cin>>T; 
	int ans = 0;
	while(T--){
		memset(a,0,sizeof(a));
		cin>>n>>m;//3 3
		int flag = 0;
		
		while(m--){
			ll o,x;//1 1
			cin>>o>>x;
			
			if(o == 1){
				a[x] = 1;
			}
			else{
				for(int i = 1;i <= n;i++){
					if(i != x){
						a[i] = 1;
					}
				}
			}
			ans++;
			int tmp_flag = 0;
			for(int i = 1;i <= n;i++){
				if(a[i] == 0){
					tmp_flag = 1;
				}
			}
			if(tmp_flag == 0){
				flag = 1;break;
			}
		}
		if(flag){
			cout<<ans;
		}else{
			cout<<-1;
		}
		cout<<endl;
	}
	
	return 0;
}

大佬求助，AC一个点