#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;
    int dem1 = 1, dem2 = 1;
    cin >> n;
    int a, b;
    
    
    int x;
    int y;
    cin >> x >> y;
    a = x;
    b = y;
    for(int a0 = 1; a0 < n; a0++){
        cin >> x >> y;
        if(x == a){
            dem1++;
        }
        if(y == b){
            dem2++;
        }
    }
    if(dem1 == n || dem2 == n) cout << "YES";
    else cout << "NO";
    return 0;
}