T = int(input())
for _ in range(T):
    S = list(input())
    S = S[::-1]
    USE = [0]*len(S)
    f = True
    tj=0
    tk=0
    if S[0]=='R':
        for i in range(len(S)):
            if not f:
                break
            if S[i]=='R':
                USE[i]=1
                tj = max(tj,i)
                for j in range(tj,len(S)):
                    if S[j]=='G' and USE[j]==0:
                        USE[j]=1
                        tj = max(tj,j)
                        tk = max(tk,j)
                        for k in range(tk,len(S)):
                            if S[k]=='W' and USE[k]==0:
                                USE[k]=1
                                tk = max(tk,k)
                                break
                        else:
                            f = False
                        break
                else:
                    f = False
    else:
        f = False
    for i in range(len(S)):
        if USE[i]==0 and S[i]!='W':
            f=False 
    for i in range(len(S)):
        if S[i]=='G':
            break
        if S[i]=='W':
            f=False
            break
    if f:
        print('possible')
    else:
        print('impossible')