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