"use strict";
function Main(input) {
    let lines = input.split("\n");
    let N = lines.shift().split(/\s/).map((v) => v - 0)[0];
    let ans = true;
    let word = [];
    for (let n = 0; n < N; n++) {
        word.push(lines.shift().trim());
    }
    const firstChar = (v) => v.charAt(0);
    const lastChar = (v) => v.charAt(v.length - 1);
    for (let n = 1; n < N && ans; n++) {
        if (lastChar(word[n-1]) != firstChar(word[n])) {
            ans = false;
        }
    }
    word.sort();
    for (let n = 0; n < N - 1 && ans; n++) {
        if (word[n] == word[n+1]) {
            ans = false;
        }
    }
    console.log(ans ? "Yes" : "No");
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
