import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

class MyScanner {
	BufferedReader br;
	StringTokenizer st;

	public MyScanner() {
		br = new BufferedReader(new InputStreamReader(System.in));
	}

	String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(br.readLine());
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	double nextDouble() {
		return Double.parseDouble(next());
	}

	String nextLine(){
		String str = "";
		try {
			str = br.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return str;
	}
}

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    	MyScanner scanner = new MyScanner();
    	
        int n = scanner.nextInt();
        
        int x1 = scanner.nextInt();
        int y1 = scanner.nextInt();
        
        int x2 = scanner.nextInt();
        int y2 = scanner.nextInt();
        
        int ok = 0;
        
        if (x1 == x2){
        	int i = 2;
	        for (i = 2; i < n; i++) {
	        	x2 = scanner.nextInt();
	            y2 = scanner.nextInt();	
	            
	            if (x1 != x2) break;
	            
	        }
	        if (i == n) System.out.println("YES");
	        else System.out.println("NO");
	    } else if (y1 == y2) {
	    	int i = 2;
	        for (i = 2; i < n; i++) {
	        	x2 = scanner.nextInt();
	            y2 = scanner.nextInt();	
	            
	            if (y1 != y2) break;
	            
	        }
	        if (i == n) System.out.println("YES");
	        else System.out.println("NO");
	    } else {
	    	System.out.println("NO");
	    }
    }
}