def solve():
    S = input()
    t = 0
    cnt = 0
    for s in S[::-1]:
        if s == "W":
            if t != 2:
                print("impossible")
                return
        elif s == "R":
            cnt += 1
            t = max(t, 1)
        else:
            cnt -= 1
            if cnt < 0:
                print("impossible")
                return
            t = 2
    if S[0] != "W" or cnt != 0:
        print("impossible")
    else:
        print("possible")

for _ in range(int(input())):
    solve()