T = int(input())
tt=[]
for _ in range(T):
    tt.append(input())
for t in tt:
    #print(len(t))
    count=0
    for i in t:
        if i=="G":
            count+=1
        elif i=="R":
            count-=1
        if count<0:
            count=-10**5
            continue
        #print(count)
    #print(count)
    if count!=0:
        print("impossible")
    else:
        print("possible")