import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        boolean isx = false;
        boolean isy = false;
        int tmpx=0,tmpy=0;
        boolean isValid = false;;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(a0==0){
                tmpx = x;
                tmpy = y;
            }
            else{
                if(!isx && !isy){
                    if(x == tmpx){
                        isx = true;
                        isValid = true;
                    }
                    else if(y == tmpy){
                        isy = true;
                        isValid = true;
                    }
                }
                if(isx){
                    if(x!=tmpx){
                        isValid = false;
                        break;
                    }                    
                }
                else if(isy){
                    if(y!=tmpy){
                        isValid = false;
                        break;
                    }
                }
                    
                    
            }
        }
        if(isValid)
            System.out.println("YES");
        else
            System.out.println("NO");
    }
}