t = int(input())

for loop in range(t):
    s = list(input())
    cnt_G = s.count("G")
    cnt_R = s.count("R")
    cnt_W = s.count("W")

    l = len(s)
    arr = [0] * l

    flag = False

    if cnt_G != cnt_R or cnt_W < cnt_G:
        print("impossible")
        continue

    for i in range(l):
        if s[i] == "W" and cnt_G > 0:
            arr[i] = 1
            cnt_G -= 1
        elif s[i] == "G":
            pass
        elif s[i] == "R":
            arr[i] = -1

    for i in range(1,l):
        arr[i] += arr[i-1]

    print(arr)
    for i in range(l):
        if s[i] == "G":
            if arr[i] == 0:
                print("impossible")
                flag = True
                break

    if not flag:
        print("possible")