def solver():
    S = input()
    S.replace("W","")
    G = 0
    for i in S:
        if i == "G":
            G += 1
        if i == "R":
            if G == 0:
                return "impossible"
            G -= 1
    if G > 0:
        return "impossible"
    return "possible"

T = int(input())
ans = [solver() for i in range(T)]
for i in ans:
    print(i)