# -*- coding: utf-8 -*-

import re

T = int(input())
for i in range(T):
    S = input()
    S = re.sub(r'W+', 'W', S)
    w = g = 0
    for x in S:
        if x == 'W':
            w += 1
        elif x == 'G':
            g += 1
        elif x == 'R':
            w -= 1
            g -= 1

        if w < 0 or g < 0:
            print('impossible')
            break
    else:
        if w == g == 0:
            print('possible')
        else:
            print('impossible')