# -*- coding: utf-8 -*-
"""
No.154 市バス
https://yukicoder.me/problems/no/154

"""
import sys
from sys import stdin
input = stdin.readline


def solve(S):
    G_stack = []
    W_stack = []

    for s in S:
        if s == 'W':
            W_stack.append(1)
        elif s == 'G':
            if len(W_stack) == 0:
                return 'impossible'
            else:
                _ = W_stack.pop()
                G_stack.append(1)
        elif s == 'R':
            if len(G_stack) == 0:
                return 'impossible'
            else:
                _ = G_stack.pop()

    if len(G_stack) != 0:
        return 'impossible'
    return 'possible'



def main(args):
    T = int(input())
    for _ in range(T):
        S = input().strip()
        ans = solve(S)
        print(ans)


if __name__ == '__main__':
    main(sys.argv[1:])