N=int(input())
for i in range(N):
    r=0
    g=0
    S=list(input())
    F=1
    for j in range(len(S)):
        if S[j]=="R":
            r+=1
        elif S[j]=="G":
            g+=1
        if r>g:
            print("impossible")
            F=0
            break
    if r==g and S[-1]=="R" and F==1:
        print("possible")
    elif F==1:
        print("impossible")