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.substring(0,1);
    var lastChar = currentWord.substring(currentWord.length-1,1);
	if(prevLastChar != undefined){
      if(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"));
