#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int ver=0;
    int hor=0;
    int ot=0;
    int n;
    cin >> n;
    vector <int>a(n);
    vector<int>b(n);
    int x,y;
    for(int i=0;i<n;i++)
        {
          cin>>x>>y;
          a[i]=x;
          b[i]=y;
        }
    int i;
    for(i=0;i<n-1;i++)
        {
           if((a[i]!=a[i+1]))
               {
                 ver=1;
               }
          if((b[i]!=b[i+1]))
              {
                hor=1;
          }
               
    }
    if(((ver==0)&&(hor==1))||((hor==0)&&(ver==1)))
        {
        cout<<"YES";
    }
    else
        cout<<"NO";
    
    return 0;
}