import std.stdio;
import std.conv;
import std.string;
import std.typecons;
import std.algorithm;
import std.array;
import std.range;
import std.math;
import std.regex : regex;
import std.container;
import std.bigint;


void main()
{
  auto n = readln.chomp.to!int;
  int[string] words;
  auto f = true;

  auto prev = readln.chomp;
  words[prev]++;

  foreach (i; 1..n) {
    auto w = readln.chomp;
    if (words.get(w, 0) || prev[$-1] != w[0]) {
      f = false;
    } else {
      words[w]++;
    }
    prev = w;
  }

  if (f) {
    writeln("Yes");
  } else {
    writeln("No");
  }
}
