for _ in range(int(input())):
    S = input()
    if S[0] != 'W' or S[-1] != 'R':
        print('impossible')
    last_g = S.rindex('G')
    if 'W' in S[last_g:]:
        print('impossible')
    S = S[:last_g] + S[last_g + 1:]
    for _ in range(1000):
        S = S.replace('WW', 'W')
        S = S.replace('GWR', '')
        S = S.replace('GR', '')
    if S == 'W':
        print('possible')
    else:
        print('impossible')