#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 prev_x, prev_y;
    int f = 0;
    int no = false;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        
        if(f == 0)
        {
            prev_x = x;
            prev_y = y;
            f = 1;
            continue;
        }
        
        if(prev_x != x && prev_y != y)
        {
            cout << "NO";
            no = true;
            break;
        }
        else
        {
            prev_x = x;
            prev_y = y;
        }    
    }
    if(!no)
        cout << "YES";
    return 0;
}