#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,c1=0,c2=0;
    cin >> n;int a[n][2];
    for(int i = 0; i< n; i++){
       for(int j=0;j<2;j++){
           cin>>a[i][j];
       }
    }for(int i=0;i<n-1;i++)
       
        {
        if(a[i][0]==a[i+1][0])
            c1++;
        if(a[i][1]==a[i+1][1])
            c2++;
    }if(c1==n-1||c2==n-1)
        cout<<"YES";
    else
        cout<<"NO";
    return 0;
}