import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)


def main():
    S = input().rstrip()[::-1]
    R = 0
    st = []
    for s in S:
        if s == "R":
            R += 1
        elif s == "G":
            if not R:
                return False
            R -= 1
            st.append(1)
        else:
            if not st:
                return False
            st.append(0)
    if R:
        return False
    st.reverse()
    W = 0
    for s in st:
        if s == 0:
            W += 1
        else:
            if not W:
                return False
            W -= 1
    return True


T = int(input())
for _ in range(T):
    if main():
        print("possible")
    else:
        print("impossible")