CodinGame - Mimetypes 1 - Ruby

n = gets.to_i
q = gets.to_i
exts = Array.new(size=n)
mts = Array.new(size=n+1, default="UNKNOWN")
n.times do |c|
    ext, mt = gets.split(' ')
    exts[c] = ext.downcase
    mts[c]  = mt
end

q.times do
    fname = gets.chomp
    start = fname.rindex('.')
    if start == nil
        dex = nil
    else
        start += 1
        len = fname.length - start
        ext = fname.slice(start, len).downcase
        dex = exts.index(ext)
    end
    dex = -1 if dex == nil
    puts mts[dex]
end