import sys
import math
import bisect
from heapq import heapify, heappop, heappush
from collections import deque, defaultdict, Counter
from functools import lru_cache
from itertools import accumulate, combinations, permutations, product

sys.setrecursionlimit(1000000)
MOD = 10 ** 9 + 7
MOD99 = 998244353

input = lambda: sys.stdin.readline().strip()
NI = lambda: int(input())
NMI = lambda: map(int, input().split())
NLI = lambda: list(NMI())
SI = lambda: input()
SMI = lambda: input().split()
SLI = lambda: list(SMI())
EI = lambda m: [NLI() for _ in range(m)]


def main():
    T = NI()
    for _ in range(T):
        S = SI()
        ok = True
        w = 0
        g = 0
        for s in S:
            if s == "G":
                g += 1
            elif s == "R":
                if g and w:
                    g -= 1
                    w -= 1
                else:
                    ok = False
                    break
            else:
                w += 1
        if g:
            ok = False
        if ok:
            print("possible")
        else:
            print("impossible")


if __name__ == "__main__":
    main()