N = int(input())

ans = ["impossible", "possible"]

for _ in range(N):
    S = input()
    rcnt = 0
    gcnt = 0

    flg = True
    for s in S[::-1]:
        if s == "R":
            rcnt += 1
        elif s == "G":
            gcnt += 1
            if gcnt > rcnt:
                flg = False
    if rcnt != gcnt:
        flg = False
    print(ans[flg])