def judge(S):
    if not (S.count('G') == S.count('R')) or S.count('W') < S.count('G'):
        return False
    
    cnt = 0
    wcnt = 0
    for x in S:
        if x == 'G':
            cnt += 1
            wcnt = 0
        elif x == 'R':
            cnt -= 1
        else:
            wcnt += 1

        if cnt < 0:
            return False
    if wcnt > 0:
        return False
    return True


N = int(input())

for i in range(N):
    S = input()

    if judge(S):
        print("possible")
    else:
        print("impossible")