n = int(input())

for i in range(n):
    flag_w = True
    white = 0
    green = 0
    buss = input()
    if len(buss)<3:
        print("impossible")
        continue
    for right in buss:
        if right=='W':
            white+=1
            flag_w=False
        elif right=='G':
            green+=1
            white-=1
            flag_w=True
            if white<0:
                print("impossible")
                break
        elif right=='R':
            green-=1
            if green<0:
                print("impossible")
                break
        else:
            print("impossible")
            break
    else:
        if green==0 and flag_w:
            print("possible")
        else:
            print("impossible")