'use strict';

function Main(inputs) {
    let input = inputs.split("\n");
    const n = parseInt(input[0], 10);
    let output = "Yes";
    input.shift();

    const ary = input.filter((w, index, array) => {
        return array.indexOf(w) === index;
    });

    if (n != ary.length) {
        output = "No";
    }

    for (let i = 1; i < n; i++) {
        if (output == "No") {
            break;
        }
        let w = input[i-1];
        let we = w.slice(-1);
        let nw = input[i];
        let nwf = nw.slice(0, 1);
        if (we != nwf) {
            output = "No";
        }
    }
    console.log(output);
}

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