import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readC(T...)(size_t n,ref T t){foreach(ref v;t)v=new typeof(v)(n);foreach(i;0..n){auto r=rdsp;foreach(ref v;t)pick(r,v[i]);}}

void main()
{
  int n; readV(n);
  string[] w; readC(n, w);

  auto h = [w[0]: true];
  foreach (i; 1..n) {
    if (w[i][0] != w[i-1][$-1] || w[i] in h) {
      writeln("No");
      return;
    }
    h[w[i]] = true;
  }

  writeln("Yes");
}
