#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 x,y,lastX,lastY;
    bool ans = true;
    cin>>x>>y;
    lastX = x;
    lastY = y;
    
    for(int i=2;i<=n;i++)
    {
        cin>>x>>y;
        
        if((lastX==x || lastY==y) && ans==true)
        {
            lastX = x;
            lastY = y;            
        }else
        {
            ans = false;
        }
    }
    
    if(ans==true)
    {
        cout<<"YES"<<endl;
    }else
    {
        cout<<"NO"<<endl;
    }
    return 0;
}