/*
Things to notice:
1. do not calculate useless values
2. do not use similar names
 
Things to check:
1. submit the correct file
2. time (it is log^2 or log)
3. memory
4. prove your naive thoughts 
5. long long
6. corner case like n=0,1,inf or n=m
7. check if there is a mistake in the ds or other tools you use
8. fileio in some oi-contest

9. module on time 
10. the number of a same divisor in a math problem
11. multi-information and queries for dp and ds problems
*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pii pair<long long,long long>
#define mp make_pair
#define pb push_back
const int mod=998244353;
const int inf=0x3f3f3f3f;
const int INF=1e18;
void solve()
{
	int n,m;
	cin>>n>>m;
	vector <pii > vec;
	while(m--)
	{
		int a,b;
		cin>>a>>b;
		vec.pb(mp(a,b));
	}
	vec.pb(mp(0,0));
	sort(vec.begin(),vec.end());
	for(int i=0;i+1<vec.size();i++) if(vec[i].fi==vec[i+1].fi&&vec[i].se!=vec[i+1].se) 
	{
		cout<<"No\n";
		return;
	}
	for(int i=0;i+1<vec.size();i++)
	{
		int d=vec[i+1].fi-vec[i].fi;
		if(vec[i].se+d==vec[i+1].se) continue;
		if(d-1<vec[i+1].se)
		{
			cout<<"No\n";
			return;
		}
	}
	cout<<"Yes\n";
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int _=1;
	cin>>_;
	while(_--) solve();
	return 0;
}