class No154:
    n = 0
    que_list = []

    def __init__(self):
        self.n = int(input())
        for i in range(self.n):
            self.que_list.append(input())

    def solve(self):
        ans_list = []
        for t in self.que_list:  # type: str
            ans_list.append(self.check_str(t))
        return ans_list

    @staticmethod
    def check_str(t):
        if not t.count("G") == t.count("R"):
            return "impossible"
        g_cnt = 0
        r_cnt = 0
        for c in t:
            if c == "G":
                g_cnt += 1
            elif c == "R":
                r_cnt += 1
            if g_cnt < r_cnt:
                return "impossible"
        return "possible"


if __name__ == "__main__":
    que = No154()
    ans = que.solve()
    for s in ans:
        print(s)