t = int(raw_input())
for _ in range(t):
    l = list(raw_input())
    l.reverse()
    ans = True
    r = 0
    g = 0
    for c in l:
        if c == 'G':
            g += 1
            if g > r:
                ans = False
                break
        elif c == 'R':
            r += 1
        elif c == 'W':
            if g == 0:
                ans = False
                break
    if ans and r != g:
        ans = False
    if ans:
        print 'possible'
    else:
        print 'impossible'