local n = io.read("*n")
local tab = {}
for i = 1,n do
    table.insert(tab, io.read("*l"))
end

local firStr = tab[1]
local myMap = {[firStr] = 1}
local len = string.len(firStr)
local endStr = string.sub(firStr, len, len)
local strStr = ""
local result = true
for i = 2, n do
    strStr = string.sub(tab[i], 1, 1)
    if strStr == endStr then
        result = false
        print("No")
        break
    end
    if myMap[tab[i]] then
        result = false
        print("No")
        break
    end
    myMap[tab[i]] = 1
end

if result then
    print("Yes")
end