#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
#include <iomanip>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETLINE( A ) string A; getline( cin , A ) 
#define FOR_LL( VAR , INITIAL , FINAL_PLUS_ONE ) for( ll VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) 
#define FOR_ITR( ARRAY , ITR , END ) for( auto ITR = ARRAY .begin() , END = ARRAY .end() ; ITR != END ; ITR ++ ) 
#define RETURN( LL , ANSWER ) const LL answer_for_contest = ( ANSWER ); cout << answer_for_contest << endl; return 0 

template <typename T> inline T Distance( const T& a , const ll& b ){ return a < b ? b - a : a - b; }

int main()
{

  CIN( ll , N );
  CIN( ll , M );
  CIN( ll , T_prev );
  CIN( ll , P_prev );
  FOR_LL( i , 1 , M ){
    CIN( ll , T );
    CIN( ll , P );
    if( T - T_prev < Distance( P , P_prev ) ){
      RETURN( string , "No" );
    }
    T = T_prev;
    P = P_prev;
  }
  RETURN( string , "Yes" );

}