# Here your code !
def possible?(s)
    lines = [0,0,0]
    s.chars.reverse.find {|c|
        if c == 'R'
            lines[2] += 1
            false
        elsif c == 'G'
            if lines[2] > 0
                lines[2] -= 1
                lines[1] += 1
                false
            else
                true
            end
        else
            if lines[0] > 0
                false
            elsif lines[1] > 0
                lines[0] += 1
                lines[1] -= 1
                false
            else
                true
            end
        end
    }.nil?
end

n = gets.to_i
n.times do
    puts possible?(gets.chomp) ? "possible" : "impossible"
end