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 horizontal = -1, horizontalCounter = 0;
        int vertical = -1, verticalCounter = 0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (a0 == 0) {
                horizontal = y;
                vertical = x;
            }
            if (horizontal == y)
                horizontalCounter++;
            if (vertical == x)
                verticalCounter++;
        }
        if (horizontalCounter == n || verticalCounter == n)
            System.out.println("YES");
        else
            System.out.println("NO");            
    }
}