#include<iostream>
#include<algorithm>
using namespace std;
int N,M;
long now,T,np,P;
main()
{
    cin>>N>>M;
    for(;M--;)
    {
        cin>>T>>P;
        if(T-now<abs(np-P))
        {
            cout<<"No"<<endl;
            return 0;
        }
        now=T;
        np=P;
    }
    cout<<"Yes"<<endl;
}