Untitled

#include <bits/stdc++.h>
using namespace std ;
#define ll long long
#define For(n) for(long long i = 0; i < n; i++)
#define endl '\n'
#define int long long
struct node {
    int id;
    int score;    
};
class cmp{
public :
    bool operator() (node n1,node n2){
        if(n1.score<n2.score)return 1;
        else if(n1.score>n2.score)return 0;
        else return n1.id>n2.id;        
    } 
};
void solve(){
    map<int,int> mp;
    int n,q,x,y;;cin>>n>>q;
    std:: priority_queue<node ,std::vector<node>,cmp>prevscores;
    cin>>x>>y;mp[x]+=y;
    int ans=0,mxscore = y,winnerteam=x;
    for(int i=1;i<q;i++){
       cin>>x>>y;
        mp[x]+= y;
        if(x==winnerteam && mp[x]<mxscore){// if winner team got fuckedup  
            mxscore = mp[x];// update mxscore
            if(prevscores.empty())continue;           
            if(mxscore<prevscores.top().score){
                ans = i;
                mxscore = prevscores.top().score;
                winnerteam = prevscores.top().id;
                prevscores.pop();
            }
            else if(mxscore==prevscores.top().score){
                if(x>prevscores.top().id){
                    ans = i;
                    mxscore = prevscores.top().score;
                    winnerteam = prevscores.top().id;
                    prevscores.pop();                    
                }               
            }
        }
        else if(mp[x]>mxscore){            
            if(winnerteam!=x)ans = i;
            node n; n.id=x,n.score=mxscore;
            prevscores.push(n);
            winnerteam = x; 
            mxscore = mp[x];
        }
        else if(mp[x] == mxscore){
            if(x<winnerteam){
                ans = i;
                winnerteam = x;
            }
            else {
                node n;n.id=x,n.score=mxscore;
                prevscores.push(n);
            }
        }
        else {
            node n;n.id=x,n.score=mxscore;
            prevscores.push(n);
        }
        // cout << winnerteam<<' '<<mxscore<<' '<<' '<<prevscores.top().first<<' '<<prevscores.top().second<<endl;
    }
    if(ans)ans++;
    // if(ans == n) ans --;
    cout << ans << endl;
}
signed main ()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);    
int t =1;
cin>>t;
while (t--){
    solve();
}    
}