n = gets.to_i
n.times do
    lines = []
    s = gets.chomp.chars.reverse
    s.each do |c|
        if c == 'R'
            lines << 0
        elsif c == 'G'
            g = lines.index(0)
            if g
                lines[g] = 1
            else
                lines << -1
                break
            end
        else
            w = lines.index(1) || lines.index(2)
            if w 
                lines[w] = 2 if lines[w] == 1
            else
                lines << -1
                break;
            end
        end
    end
    puts lines.all? {|v| v == 2 } ? "possible" : "impossible"
end