#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q,flagx=0,flagy=0;
    cin>>q;
    int n,maxx=10000,maxy=10000,minx=10000,miny=10000;
    cin>>n;
    
    for(int i=0;i<n;i++)
        {
        int x,y;
        cin>>x>>y;
        if(minx<x&&flagx==0)
        {flagx=1;
            minx=x;
        }
        else
        {cout<<"NO";return 0;}
        if(miny<y&&flagy==0)
        {flagy=1;miny=y;}
        else
           { cout<<"NO";return 0;}
        if(maxx>x&&flagx==0){flagx=1;
                             miaxx=x;}else
          {  cout<<"NO";return 0;}
        if(maxy>y&&flagy==0){flagy=1;
                             maxy=y;}else
        { cout<<"NO";return 0;}
        
        
    }
    cout<<"YES";
    return 0;
}