T = int(input())
for i in range(T):
    S = input()
    cnt = 0
    for j in range(len(S)):
        if S[j] == 'G':
            cnt += 1
        elif S[j] == 'R':
            cnt -= 1
        if cnt < 0:
            print('impossible')
            break
    else:
        if cnt == 0:
            print('posiible')
        else:
            print('impossible')