def main():
    n = int(input())

    for _ in range(n):
        memo = input()[::-1]
        W, G, R, pair_GR = 0, 0, 0, 0
        last_R, last_G, b = False, False, True

        for s in memo:
            if s == 'R':
                R += 1
                last_R = True

            elif s == 'G' and last_R:
                last_G = True
                if R > 0:
                    R -= 1
                    pair_GR += 1
                else:
                    print('impossible')
                    b = False
                    break

            elif s == 'W' and last_R and last_G:
                if pair_GR == 0:
                    print('impossible')
                    b = False
                    break
                elif pair_GR > 0:
                    W += 1

            else:
                print('impossible')
                b = False
                break

        if R == 0 and b:
            print('possible')

main()