#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int T; cin >> T;
    while(T--){
        string s; cin >> s;
        bool ok = true;
        int Ws = 0,Gs = 0,Rs = 0;
        for(auto c : s){
            if(c == 'W') Ws++;
            else if(c == 'G') Gs++;
            else Rs++;
            if(Ws < Gs || Gs < Rs) ok = false;   
        }
        if(Gs != Rs || Rs == 0) ok = false;
        if(s.back() != 'R') ok = false;
        for(int i=s.size(); i--;){
            if(s.at(i) == 'G') break;
            else if(s.at(i) == 'W'){ok = false; break;}
        }
        cout << (ok?"possible":"impossible") << "\n";
    }
}