import std.stdio;
import std.algorithm;
import std.conv;
import std.string;

void main()
{
	auto n = to!int(chomp(readln()));
	string[] ws;
	ws ~= chomp(readln());
	bool isYes = true;
	foreach (i; 1..n)
	{
		ws ~= chomp(readln());
		if (ws[i-1][$-1] != ws[i][0])
		{
			isYes = false;
			break;
		}
		else if (countUntil(ws[0..$-1], ws[$-1]) != -1)
		{
			isYes = false;
			break;
		}
	}

	if (isYes)
		writeln("Yes");
	else
		writeln("No");

	stdout.flush();
}