N = int(input())
P = [input() for _ in range(N)]

for pat in P:
    wcount = 0
    gcount = 0
    for i in range(len(pat)):
        if pat[i] == 'W':
            wcount += 1
        if pat[i] == 'G':
            gcount += 1
            if wcount < gcount:
                print('impossible')
                break
        if pat[i] == 'R':
            if wcount < 1 or gcount < 1:
                print('impossible')
                break
            wcount -= 1
            gcount -= 1
    else:
        flag = 'W' in pat[::-1][:pat[::-1].index('G')]
        if pat[-1] != 'R' or gcount != 0 or flag:
            print('impossible')
        else:
            print('possible')