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 a = in.nextInt();
        int b = in.nextInt();
        boolean aH = true;
        boolean bH = true;
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(x!=a)aH=false;
            if(y!=b)bH=false;
        }
        if(aH||bH)System.out.println("YES");
        else{System.out.println("NO");}
    }
}