T = int(input())
for _ in range(T):
    S = list(input())
    cnt = 0
    flag = 1
    for s in S:
        if s == "G":
            cnt += 1
        elif s == "R":
            cnt -= 1
        if cnt < 0:
            print("impossible")
            flag = 0
            break
    if flag == 0:
        continue
    print("possible") if cnt == 0 else print("impossible")