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) {
        int horizontal = 0;
        int vertical = 0;
        int difH = 0;
        int difV = 0;
        String answer = "YES";
        
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (a0 == 0) {
                vertical = x;
                horizontal = y;
            } else {
                if (x != vertical) {
                    difV = 1;
                }
                if (y != horizontal) {
                    difH = 1;
                }
            }
        }
        if (difV == 0 || difH == 0) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}