import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)


def main():
    S = input().rstrip()
    G = 0
    for s in S:
        if s == "G":
            G += 1
        elif s == "R":
            if not G:
                print("impossible")
                return
            G -= 1
    if G:
        print("impossible")
    else:
        print("possible")
    return


T = int(input())
for _ in range(T):
    main()