t = int(input())
for _ in range(t):
    s = input()
    r = [0,0,0]
    ok = 1
    for i in s:
        if i=="W":
            r[0] += 1
        if i=="G":
            if r[1] >= r[0]: ok = 0
            r[1] += 1
        if i=="R":
            if r[2] >= r[1]: ok = 0
            r[2] += 1
    if r[1] != r[2]: ok = 0
    print("possible " if ok else "impossible")