N = int(input())
P = [input() for _ in range(N)]

for pat in P:
    if 'W' not in pat or 'G' not in pat or 'R' not in pat:
        print('impossible')
        continue
    p = pat[:]
    for i in range(len(pat)):
        if pat[i] == 'G':
            if 'W' not in p[:i]:
                print('impossible')
                break
            p = p[:i].replace('W', 'X', 1) + p[i:]
            if 'R' not in p[i+1:]:
                print('impossible')
                break
            p = p[:i+1] + p[i+1:].replace('R', 'S', 1)
    else:
        if p[-1] != 'S' or 'R' in p or 'W' in p[::-1][:p[::-1].index('G')]:
            print('impossible')
        else:
            print('possible')