def answer():
    S = list(input())
    W = [int(i == 'W') for i in S]
    G = [int(i == 'G') for i in S]
    R = [int(i == 'R') for i in S]
    N = len(S)
    from itertools import accumulate
    
    SW = list(accumulate(W))
    SG = list(accumulate(G))
    SR = list(accumulate(R))
    for i in range(N):
        if SW[i]>=SG[i]>=SR[i]:
            continue
        else:
            print('impossible')
            return
    
    if SG[-1] != SR[-1]:
        print('impossible')
        return
    print('possible')
    return

for _ in range(int(input())):
    answer()