#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int n=0,t=0;
  int N,M;
  cin>>N>>M;
  for(int i=0;i<M;i++){
      int T,P;
      cin>>T>>P;
      if(abs(P-n) > T-t){
          cout<<"No"<<endl;
          return 0;
      }
      t = T;
      n = P;
  }
  cout<<"Yes"<<endl;
}