t = int(input())
for _ in range(t):
    s = input()
    w=g=r=0
    ok = 1
    for i in s[::-1]:
        if i=="W":
            if g:
                w += 1
                g -= 1
            elif w==0:
                ok = 0
        if i=="G":
            if r==0: ok = 0
            g += 1
            r -= 1
        if i=="R":
            r += 1
    if r or g: ok = 0
    print("possible" if ok else "impossible")