for i in range(int(input())):
    ok = True
    S = input()
    cntw = cntg = cntr = 0
    for s in S:
        if s == 'W': cntw += 1
        if s == 'G': cntg += 1
        if s == 'R': cntr += 1
        if cntw < cntg or cntg < cntr:
            ok = False
            break
    if (cntw != 0 and cntg == 0) or (cntg != cntr):
        ok = False
    if ok:
        bus = cntg
        for s in S:
            if s == 'G':
                bus -= 1
            if s == 'W' and bus == 0:
                ok = False
                break

    if ok:
        print('possible')
    else:
        print('impossible')