for j in range(int(input())):
    #print(j)
    W,R,G = 0,0,0
    lastw = 0
    lastg = 0
    S = input()
    for i,s in enumerate(S):
        if s == "W":
            W += 1
            lastw = i
        if s == "R":
            R += 1
        if s == "G":
            G += 1
            lastg = i
        if W < G or G < R:
            print("impossible")
            break

    else:
        if lastw > lastg:
            print("impossible")
            continue
        if R == G and R > 0:
            print("possible")
        else:
            print("impossible")