import std.stdio, std.string, std.range, std.conv, std.array, std.algorithm, std.math, std.typecons;

void main() {
    auto N = readln.chomp.to!int;
    string[] wordList;
    bool result = true;
    foreach (i; 0..N) {
        auto W = readln.chomp;
        scope(exit) wordList ~= W;
        if (wordList is null) continue;
        if (wordList.canFind(W)) result = false;
        if (wordList.back.back != W.front) result = false;
    }
    writeln(result ? "Yes" : "No");
}

