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:
        QR = [0,0]
        QG = [0,0]
        while C:
            color = C[0]
            C = C[1:]
            if color == "R":
                QR[0] += 1
            elif color == "G" and QR[0]>QG[0]:
                QG[0] += 1
            elif color == "G":
                print("impossible")
                break
            elif QR[0]*QG[0]==0 and color == "W":
                print("impossible")
                break
            elif QR[0]>QR[1] and QG[0]>QG[1]:
                QR[1] += 1
                QG[1] += 1
        else:
            if QR[0]-QR[1] == 0 and QG[0]-QG[1]==0:
                print("possible")
            else:
                print("impossible")
    else:
        print("impossible")