gets.to_i.times do
  l = gets
  line = l
  a,b = 1,1
  while line !~ /th(at|is)/
    line = l.unpack("C*").map{|n|
      n = (n >= 97 and n <= 122) ? (a*n+b)%26+97 : n
    }.pack("C*")
    b=(b+1)%26
    if b==0
      begin
        a+=1
      end while a.gcd(26) != 1
    end
  end
  puts line
end