T = int(input())
for _ in range(T):
    S = input()
    w = 0
    g = 0
    r = 0
    flag = True
    for s in S:
        if s == 'W':
            w += 1
        if s == 'G':
            if w == 0:
                print('impposible')
                flag = False
                break
            else:
                w -= 1
        if s == 'R':
            if g == 0:
                print('impposible')
                flag = False
                break
            g -= 1
        if flag:
            if g == 0:
                print('possible')
            else:
                print('impposible')