t = int(input())
ans = []
for i in range(t):
    s = list(input())
    f = 0
    flag = 1
    count_w = 0
    count_g = 0
    count_r = 0
    while s:
        wgr = s.pop(0)
        if wgr == 'W':
            count_w += 1
            flag = 1
        elif wgr == 'G':
            count_g += 1
            flag = 0
        elif wgr == 'R':
            count_r += 1
        if count_g < count_r or count_w < count_g:
            f = 1
    if f == 0 and flag == 0 and count_w >= count_g == count_r:
        ans.append('possible')
    else:
        ans.append('impossible')
for j in ans:
    print(j)