#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

void in(){} template<typename Head,typename... Tail> void in(Head&& head,Tail&&... tail){cin>>head;in(forward<Tail>(tail)...);}

template<class S,class T>void Inparray1(S& a,T& b,int n){for(int i=0;i<n;i++) cin>>a[i]>>b[i];}

void flagfunc3(bool flag){cout<<(flag?"Yes\n":"No\n");}

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  int n,m,p;
  in(n,m);
  ll t;

  //現在区画 0 にいて、時刻は 0
  int a=0,b=0;
  bool flag=true;
  rep(i,m){
    in(t,p);
    if((t-a)>=(p-b)){
      a=t;
      b=p;
    }else{
      flag=false;
      break;
    }
  }
  flagfunc3(flag);
}