#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=-1,b=-1,ans=0;
    cin>>a>>b;
     int x;
        int y;
      cin >> x >> y;
    
    if(x==a)
    for(int a0 = 0; a0 < n-2; a0++){
       cin>>x>>y;
        if(x!=a)
            ans=1;
    }
    else if(y==b)
       for(int a0 = 0; a0 < n-2; a0++){
       cin>>x>>y;
        if(y!=b)
            ans=1;
    } 
    else
        ans=1;
    if(ans==1)
        cout<<"NO";
    else
        cout<<"YES";
    return 0;
}