#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 arr[2*n];
    int h = 0;
    int count1 = 0;
    int count2 = 0;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        arr[h++] = x;
        arr[h++] = y;
    }
    for(int i = 2; i < 2*n; i++)
    {
        if(i%2 == 0)
        {
            if(arr[i-2] == arr[i]) 
                count1++;
        }
        else
            {
            if(arr[i-2] == arr[i])
                count2++;
        }
    }
    if(count1 == n-1 || count2 == n-1)
        cout << "YES";
    else 
        cout << "NO";
    return 0;
}