T=int(input())
for i in range(T):
    S=input()
    temp=0
    ans='possible'
    for j in range(len(S)):
        if S[j]=='G':
            temp+=1
        elif S[j]=='R':
            temp-=1
            if temp<0:
                ans='impossible'
    print(ans if temp==0 else 'impossible')