import java.io.*;
import java.util.*;
public final class hack_june_a
{
    static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static FastScanner sc=new FastScanner(br);
    static PrintWriter out=new PrintWriter(System.out);
	
	public static void main(String args[]) throws Exception
	{
		int n=sc.nextInt();
		int[] cnt1=new int[1000],cnt2=new int[1000];
		for(int i=0;i<n;i++)
		{
			int num1=sc.nextInt()+100,num2=sc.nextInt()+100;
			cnt1[num1]++;cnt2[num2]++;
		}
		boolean ans=false;
		for(int i=0;i<1000;i++)
		{
			if(cnt1[i]==n || cnt2[i]==n)
			{
				ans=true;
				break;
			}
		}
		out.println((ans)?"YES":"NO");
		out.close();
	}
}
class Node
{
	
}
class FastScanner
{
    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }
	
    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
	
	public String next() throws Exception {
		return nextToken().toString();
	}
	
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}