#include <iostream>
using namespace std;
int main() {
    int n,m;
    cin>>n>>m;
    int t,p;
    int t0=0,p0=0;
    bool f=1;
    for (int i=0;i<m;i++){
        cin>>t>>p;
        if(t==0 and p!=0) f=0;
        t0+=abs(p-p0);
        if(t<t0) f=0;
        t0=t;
        p0=p;
    }
    if(f)  cout<<"Yes"<<endl;
    else cout<<"No"<<endl;
return 0;
}