for _ in xrange(input()):
    s = raw_input()
    w, g, r = s.count('W'), s.count('G'), s.count('R')
    if w == 0 or g == 0 or r == 0:
        print 'impossible'
        continue
    if w < r or w < g:
        print 'impossible'
        continue
    if s.rindex('W') > s.rindex('G') or s.rindex('W') > s.rindex('R'):
        print 'impossible'
        continue
    
    left = 0
    for c in s:
        if c == 'G':
            left += 1
        elif c == 'R':
            left -= 1
        if left < 0:
            break
    if left != 0:
        print 'impossible'
        continue
    print 'possible'