#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 n;
    cin >> n;
    
    int a[n][2];
    int count1=0,count2=0;
    for(int i = 0; i < n; i++)
    {
      cin>>a[i][0]>>a[i][1];
        if(i>=1)
      {
          if(a[i-1][0]==a[i][0])
              count1++;
            if(a[i-1][1]==a[i][1])
              count2++;
      
        }
    
    }
    
    if(count1==(n-1) || count2==(n-1))
       cout<<"YES";
    else
        cout<<"NO";
    
    return 0;
}