N = io.read("*n", "*l")
W = {}
for i=1, N do
    W[i]=io.read()
end

checker = true
for i=1, N-1 do
    if string.sub(W[i], -1, -1) ~= string.sub(W[i+1], 1, 1) then
        checker = false
    end
end

table.sort(W)
for i=1, N-1 do
    if W[i] == W[i+1] then
        checker = false
    end
end

if checker then
    print("Yes")
else
    print("No")
end