import java.util.Scanner;

public class mainclass {
public static void main(String[] args) {
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	
	int [][]a=new int[n][2];
	
	int i,j;
	for(i=0;i<n;i++)
	{
		for(j=0;j<2;j++)
		{
			a[i][j]=sc.nextInt();
		}
	}
int count=1;
	
	
	for(i=1;i<n;i++)
	{
		if((a[i-1][0]==a[i][0])||a[i-1][1]==a[i][1])
		{
           count++; 
        }
	}
	if(count==n)
		System.out.println("YES");
	else
		System.out.println("NO");
	
	
}
}