#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 x1=-1;
    int y1=-1;
    bool flag=true;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        
        if(x1==-1 && y1==-1)
        {
            x1=x;
            y1=y;
            
        }
        else
        {
            if(x!=x1 && y!=y1)
            { flag=false;break;}
        }
    }
    
    if(flag)
        cout <<"YES";
        else
        cout <<"NO";
    return 0;
}