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