#include <iostream>
using namespace std;
int main(){
    int n,m;cin>>n>>m;
    int now=0;
    int time=0;

    for(int i=0;i<m;i++){
        int t,p;cin>>t>>p;
        if(t-time>=abs(p-now)){
            t=time;
            now=p;
        }
        else{
            cout<<"No"<<endl;
            return 0;
        }
    }
    cout<<"Yes"<<endl;

    return 0;
}