def delete_before(s, c, n):
    for i in range(n - 1, -1, -1):
        if s[i] == c:
            s[i] = '#'
            return True
    return False

T = int(input())
for t in range(T):
    S = list(input())
    if S[-1] != 'R':
        print('impossible')
        continue
    for i, c in enumerate(S):
        if c == 'G':
            if not delete_before(S, 'W', i):
                print('impossible')
                break
        if c == 'R':
            if not delete_before(S, 'G', i):
                print('impossible')
                break
    else:
        print('possible')