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

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

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

            elif s == 'G' and G < R:
                G += 1
                pair_GR += 1

            elif s == 'W' and pair_GR > 0 and pair_GR > W:
                W += 1

            elif s == 'W' and pair_GR <= W and not pair_GR == 0:
                continue

            else:
                b = False
                break

        if b and pair_GR == W and R == G:
            print('possible')
        else:
            print('impossible')

main()