#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> ostream & operator<<(ostream & os, vector<T> const &);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }
template<class T, class U> ostream & operator<<(ostream & os, pair<T,U> const & p){ return os << "(" << p.first << ", " << p.second << ") "; }
template<class T> ostream & operator<<(ostream & os, vector<T> const & v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif

int main(){
#ifdef LOCAL
    freopen("in","r",stdin);
#endif

    int n;
    cin >> n;
    rep(_,n){
        string s;
        cin >> s;
        dump(s);
        typedef priority_queue<int> pq;
        pq r,g,w;
        rep(i,s.size()){
            if(s[i]=='R') r.push(i);
            if(s[i]=='G') g.push(i);
            if(s[i]=='W') w.push(i);
        }
        bool ok = true;
        if(s.size() < 2) ok = false;
        if(s[0] != 'W') ok = false;
        if(s[s.size()-1] != 'R' || s[s.size()-2] == 'W') ok = false;
        if(ok && (r.size()==0 || g.size()==0)) ok = false;
        if(ok && r.size() != g.size()) ok = false;
        if(ok && w.size() < r.size()) ok = false;
        // if(ok && w.size()%r.size() != 0) ok = false;
        while(ok && r.size()){
            int a = r.top();
            r.pop();
            if(g.size()==0){
                ok = false;
                break;
            }
            int b = g.top();
            g.pop();
            if(a < b){
                ok = false;
                break;
            }
        }
        if(g.size()) ok = false;
        puts(ok ? "possible" : "impossible");
    }
}