import sys
input=sys.stdin.readline

T=int(input())
for _ in range(T):
    S=input()[:-1]
    X=0
    F=1
    for s in S:
        if s=="G":
            X+=1
        elif s=="R":
            if X==0:
                F=0
            else:
                X-=1

    print("possible" if X==0 and F==1 else "impossible")