#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 n,count=0;
    vector <int> a,b;
    cin>>n;
    for(int j=0;j<n;j++)
        {
        int x,y;
        cin>>x>>y;
        a.push_back(x);
        b.push_back(y);
    }
    if(a[0]!=a[1]&&b[0]!=b[1])
        cout<<"NO";
    else{
        if(a[0]==a[1])
        {
        for(int i=2;i<n;i++)
            {
            if(a[0]!=a[i])
                {
                count=1;
                break;
            }
        }
    }
    else if(b[0]==b[1])
        {
        for(int i=2;i<n;i++)
            {
            if(b[0]!=b[i])
                {
                count=1;
                break;
            }
        }
    }
    if(count)
        cout<<"NO";
    else
        cout<<"YES";
    }
    return 0;
}