function Main(input){
    //console.log(input.split("\n"));
    input = input.split("\n");
    //console.log(input);

    //console.log(typeof input[0] + " " + input[0]);

    var N = parseInt(input[0],10);
    //console.log(typeof N + " " + N);

    input.shift();
    //console.log(input);
    var w = input;

    for(var i = 0; i < N; i++){
        for(var j = i + 1; j < N; j++){
            if(w[i] === w[j]){
                console.log("No");
                return;
            }
        }
    }

    for(var i = 0; i < N - 1; i++){
        if(w[i].slice(-1) !== w[i + 1].slice(0,1)){
            console.log("No");
            return;
        }
    }

    console.log("Yes");

}

Main(require("fs").readFileSync("/dev/stdin","utf8"));