T = int(input())
for i in range(T):
    possible = True
    S = input()
    cnt = {'W': 0, 'G': 0, 'R': 0}
    for j in range(len(S)):
        cnt[S[j]] += 1
        if S[j] == 'G' and cnt['G']>cnt['W']:
            possible = False
        if S[j] == 'R' and not cnt['R']<=cnt['G']<=cnt['W']:
            possible = False
    if cnt['G'] != cnt['R']:
        possible = False
    if possible:
        print('possible')
    else:
        print('impossible')