#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;
    //vector<vector<int>> P(n,vector<int>(2));
     int countx = 1, county = 1;
    int p0, p1;
    cin >> p0 >> p1;
    for(int a0 = 1; a0 < n; a0++)
    {
        int x;
        int y;
        cin >> x >> y;


        if(p0 == x)
            countx++;
        else if(p1 == y)
            county++;
    }
    if((countx == n) || (county == n)) 
        cout<<"YES";
    else 
        cout <<"NO";
    return 0;
}