Word Cube in Lua

-- q contains all the letters from s?
function containedIn(s,q)
    local r
    for i=1,#s do
        q,r=string.gsub(q,string.sub(s,i,i),"",1)
        if r==0 then return false end
    end
    return true
end

function cubeWords(q)
    q5=string.sub(q,5,5)
    for l in io.lines("words.txt") do
        l=string.lower(l)
        if #l>3 and string.find(l,q5) and containedIn(l,q) then
        print(l)
        end
    end
end

cubeWords("ncbcioune")