#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 last_x , last_y;
         cin >> last_x >> last_y;
    bool ok=true;
    for(int a0 = 1; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        
        if(x != last_x && y!= last_y) {
            ok = false;
            break;
        }
    }
    
    if(ok) {
        cout<<"YES";
    } else {
        cout<<"NO";
    }
    
    
    return 0;
}