function Main(input) {
  var arr = input.split('\n');
  var nums = arr[0];
  var set = new Set();
  var prevLastChar = undefined;
  for(var i=1;i<arr.length;++i){
    var currentWord = arr[i];
    var firstChar = currentWord.substr(0,1);
    var lastChar = currentWord.substr(currentWord.length-1,1);
    if(prevLastChar != undefined && prevLastChar != firstChar){
      console.log('No');
      return;
    }
    if(set.has(currentWord)){
      console.log('No');
      return;
    }
    set.add(currentWord);
    prevLastChar = lastChar;
  }
  console.log('Yes');
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
