for _ in range(int(input())):
    S = input()
    r, g, w = 0, 0, 0
    ls = ""
    f = True
    for s in S:
        if s == "R":
            r += 1
        else:
            ls = s
            if s == "G":
                g += 1
            else:
                w += 1
        if w < g or g < r:
            f = False
    if not f or r != g or ls != "G":
        print("impossible")
    else:
        print("possible")