n = gets.to_i
n.times do
    lines = [0,0,0]
    s = gets.chomp.chars.reverse
    s.each do |c|
        if c == 'R'
            lines[0] += 1
        elsif c == 'G'
            if lines[0] > 0
                lines[0] -= 1
                lines[1] += 1
            else
                break
            end
        else
            if lines[1] > 0
                lines[1] -= 1
                lines[2] += 1
            elsif lines[2] < 1
                break;
            end
        end
    end
    puts lines[0] == 0 && lines[1] == 0 && lines[2] > 0 ? "possible" : "impossible"
end