procedure main(a)
    words := set()
    found := 0
    every word := map(!&input) do {
        if member(words, reverse(word)) then {
            if (found +:= 1) <= 5 then write("\t",reverse(word),"/",word)
            }
        else insert(words, word)
        }
    write("\nFound ",found," semordnilap words")
end