T=int(raw_input())
for i in range(T):
    S=raw_input()
    Wcnt=0
    Gcnt=0
    ok=True
    for s in S:
        if s=='W':
            ok=False
            Wcnt+=1
        if s=='G':
            ok=False
            if Wcnt < 1:
                break
            Wcnt-=1
            Gcnt+=1
        if s=='R':
            if Gcnt <= 0:
                ok=False
                break
            ok=True
            Gcnt-=1
    if ok:
        print 'possible'
    else:
        print 'impossible'