#include <bits/stdc++.h>
using namespace std;

int main(){
  int N, M;
  cin >> N >> M;
  
  long ct = 1, cp = 0;
  while(M--){
    long T, P;
    cin >> T >> P;
    if((T - ct) < abs(P - cp)){
      cout << "No";
      return 0;
    }
    ct = T, cp = P;
  }
  
  cout << "Yes";
}