#include <bits/stdc++.h>
using namespace std;

int main( )
{
    string s, pre;
    int n, sig = 1;
    cin >> n >> pre;
    map<string, int> mp;
    mp[pre]++;
    for (int i = 1; i < n; i++)
    {
        cin >> s;
        if (mp[s] > 0)
        {
            sig = 0;
        }
        if (s[0] != pre[pre.size( ) - 1])
        {
            sig = 0;
        }
        mp[s]++;
        pre = s;
    }

    if (sig == 1)   cout << "Yes\n";
    else            cout << "No\n";

    return 0;
}