#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <map>
using namespace std;
typedef long long ll;
#define rep(i,n) for (int i=0;i < (int)(n);i++)


int main(){
   int n,m;
   cin >> n >> m;
   int pos = 0;
   int time = 0;
   rep(i,m){
      int t,p;
      cin >> t >> p;
      if (abs(pos-p) > t-time){
         cout << "No" << endl;
         return 0;
      }
      time = t;
      pos = p;
   }
   cout << "Yes" << endl;

  
  return 0;
}