T = int(input())
S = [input() for _ in range(T)]

ans = []
for i in range(T):
    s = S[i]
    L = len(s)
    cnt = 0
    g = False
    for i in range(L-1, -1, -1):
        if s[i] == 'R':
            cnt += 1
        elif s[i] == 'G':
            cnt -= 1
            f = True
        if cnt < 0 or (s[i] == 'W' and g):
            ans.append('impossible')    
            break
    else:
        ans.append('possible')
        
print(*ans, sep='\n')