#include <cmath>
#include <queue>
#include <stack>
#include <string>
#include <cstdio>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;


int main(){
    int n;
    cin >> n;
    vector <int> v, h;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        v.push_back(x);
        h.push_back(y);
    }
    int check = v[0];
    int c = 0;
    for(int i = 1; i < v.size(); i++)
        {
            if(v[i]!=check)
            {
                c++;
                break;
            }
        }
    if(c != 0)
    {
        check = h[0];
        for(int i = 1; i < h.size(); i++)
        {
            if(h[i]!=check)
            {
                cout << "NO" <<endl;
                break;
            }
        }
    }
    else
        cout << "YES" << endl;
    return 0;
}