function main(input) {
  var N = input[0]-0;
  var ans = "Yes";
  var map = {};
  var next = "";
  for(var i=1;i<=N;i++){
    var str = input[1];
    if(map[str]){
      ans = "No";
      break;
    }else{
      if(next!=""){
        if(str[0] != next){
          ans = "No";
          break;
        }
      }
      next = str[str.length-1];
      map[str] = true;
    }
  }
  console.log(ans);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"))
