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();
        if (n < 1)
            return;
        
        int prevrow = in.nextInt();
        int prevcol = in.nextInt();
        boolean samerow = true;
        boolean samecol = true;
        
        for(int a0 = 0; a0 < n - 1; a0++){
            int row = in.nextInt();
            int col = in.nextInt();
            
            if (row != prevrow)
                samerow = false;
            
            if (col != prevcol)
                samecol = false;
            
        }
        
        if (samerow || samecol) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}