for _ in range(int(input())):
    r, g = 0, 0
    S = input()
    for c in S[::-1]:
        if c == 'R':
            r += 1
        if c == 'G':
            if r > 0:
                g += 1
            else:
                print('impossible')
                break
        if c == 'W':
            if g == 0:
                print('impossible')
                break
    else:
        if r == g and S[0] == 'W':
            print('possible')
        else:
            print('impossible')