N = int(input())

ans = ["impossible", "possible"]

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

    flg = True
    for s in S[::-1]:
        if s == "R":
            rcnt += 1
        elif s == "G":
            if rcnt == 0:
                flg = False
            gcnt += 1
            rcnt -= 1
        elif s == "W":
            if gcnt:
                wcnt += 1
                gcnt -= 1
            elif wcnt == 0:
                flg = False
    if rcnt or gcnt:
        flg = False
    print(ans[flg])