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

using Int = long long;
const char newl = '\n';

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
template<typename T> void drop(const T &x){cout<<x<<endl;exit(0);}
template<typename T=Int>
vector<T> read(size_t n){
  vector<T> ts(n);
  for(size_t i=0;i<n;i++) cin>>ts[i];
  return ts;
}

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  Int n,m;
  cin>>n>>m;

  Int cur=0,lst=0;
  for(Int i=0;i<m;i++){
    Int t,p;
    cin>>t>>p;
    if(abs(cur-p)>t-lst) drop("No");
    lst=t;
    cur=p;
  }
  drop("Yes");
  return 0;
}