N = int(input())
for _ in range(N):
    C = input()[::-1]
    cr,cg,cw = C.count("R"),C.count("G"),C.count("W")
    if cr == cg and cw >= cr:
        Q = [0,0]
        while C:
            color = C[0]
            C = C[1:]
            if color == "R":
                Q[0] += 1
            elif color == "G" and Q[0]>Q[1]:
                Q[1] += 1
            elif color == "G":
                print("impossible")
                break
            elif Q[0]*Q[1]==0 and color == "W":
                print("impossible")
                break
            else:
                Q[0] -= 1
                Q[1] -= 1
        else:
            if Q[0] == 0:
                print("possible")
            else:
                print("impossible")
    else:
        print("impossible")