function Main(input){
    input = input.split("\n");
    var N = parseInt(input[0],10);
    input.shift();
    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"));