// I SELL YOU...! 
#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<chrono>
#include<iomanip>
#include<map>
#include<set>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using TP = tuple<ll,ll,ll>;
void init_io(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(18);
}
signed main(){
  init_io();
  ll t;
  string s;
  cin >> t;
  for(int i=0;i<t;i++){
    cin >> s;
    ll wc=0,gc=0,rc=0;
    bool can =true;
    for(auto c:s){
      if(c=='W') wc++;
      else if(c=='G'){
        if(wc==0){
          can = false;
          break;
        }else{
          wc--;
          gc++;
        }
      }else{
        if(gc==0){
          can = false;
          break;
        }
        gc--;
        rc++;
      }
    }
    if(gc) can = false;
    if(!rc) can = false;
    if(can) cout <<"possible\n";
    else cout <<"impossible\n";
  }
}