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

T = int(input())
for i in range(T):
    S = input()
    cnt = 0
    for x in S:
        if x == 'G':
            cnt += 1
        elif x == 'R':
            cnt -= 1

        if cnt < 0:
            print('impossible')
            break
    else:
        if cnt > 0:
            print('impossible')
        else:
            print('possible')