import sys
def I(): return int(sys.stdin.readline().rstrip())
def S(): return sys.stdin.readline().rstrip()


T = I()
for _ in range(T):
    U = S()
    r,g,w = 0,0,0
    for u in U:
        if u == 'R':
            if g > 0:
                g -= 1
            else:
                print('impossible')
                break
        elif u == 'G':
            if w > 0:
                w -= 1
                g += 1
            else:
                print('impossible')
                break
        else:
            w += 1
    else:
        if g == 0:
            print('possible')
        else:
            print('impossible')