#include<bits/stdc++.h>

using namespace std;
using ll=long long;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll t;
  cin >> t;
  while(t--){
    ll n,m;
    cin >> n >> m;
    ll lef=0,rig=0;
    for(ll i=0;i<m;i++){
      ll a,b;
      cin >> a >> b;
      if(i==0){
        lef=a;
        rig=a+b-1;
      }
      else{
        lef=max(lef,a-b)+b;
        rig=min(rig,a-1)+b;
      }
    }
    if(lef<=rig){cout << "Yes\n";}
    else{cout << "No\n";}
  }
  return 0;
}