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


int main() {
    int n,i,c=0,d=0;
    cin>>n;
     int a[n],b[n];
    for(i=0;i<n;i++)
        {
        cin>>a[i]>>b[i];
    }
    for(i=1;i<n;i++)
        {
        int comp=a[0];
        if(a[i]!=comp)
            c++;
    }
    for(i=1;i<n;i++)
        {
        int comp=b[0];
        if(b[i]!=comp)
            d++;
    }
    if(c==0 || d==0)
        cout<<"YES";
    else
        cout<<"NO";
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}