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();
        int tempx = in.nextInt();
        int tempy = in.nextInt();
        boolean flag1=true;
        boolean flag2=true;
        for(int i = 0; i < n-1; i++){
            int x = in.nextInt();
            if(tempx!=x){flag1=false;}
            int y = in.nextInt();
            if(tempy!=y){flag2=false;}
            }
        
if(flag1||flag2){System.out.println("YES");}
else System.out.println("NO");
    
}
}