def solve(S):
    wg, gr = 0, 0
    w_flag = True
    for s in S:
        if s == 'W':
            wg += 1
            w_flag = False
        elif s == 'G':
            if not wg:
                return False
            w_flag = True
            wg -= 1
            gr += 1
        elif s == 'R':
            if not gr:
                return False
            gr -= 1
    return w_flag and not gr


T = int(input())
for _ in range(T):
    S = input()
    print('possible' if solve(S) else 'impossible')