def solve(S):
    ct = 0
    for s in S:
        if s == 'G':
            ct += 1
        elif s == 'R':
            ct -= 1
            if ct < 0:
                return 'impossible'
    return 'possible' if ct == 0 else 'impossible'


N = int(input())
for _ in range(N):
    print(solve(input()))