#include <iostream>
using namespace std;
int main()
{
    int n;   cin >> n;
    int arr1[n] , arr2[n] , ezafe[500];
    int i = 0; 
    while ( i < 500 )
    {
        ezafe[i] = 0;
        i ++;
    }

    for ( int i = 0 ; i < n ; i ++ )
    {
        cin >> arr1[i] >> arr2[i];
        if ( arr1[i] <= 499 )
        {
            ezafe[arr1[i]] ++;
        }

        if ( arr2[i] <= 499 )
        {
            ezafe[arr2[i]] ++;
        }
    }

    int counter = 0;
    for ( int i = 0 ; i < n ; i ++ )
    {
        if ( ezafe[arr1[i]] == 2 )
        {
            counter ++;
        }

        if ( i == n - 1 )
        {
            if ( counter == n )
            {
                cout << "Yes";
            }

            else 
            {
                cout << "No";
            }
        }
    }



    return 0;
}