#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define clr(a, b) memset((a), (b) ,sizeof(a))

#define MOD 1000000007

int main(){
    int n;
    cin>>n;
    rep(i,0,n){
        string s;
        cin>>s;
        {
        string ss = s;
        reverse(all(ss));
        int flag = 0;
        int flag1 = 0;
        rep(i,0,ss.sz){
          if(flag == 0 && (ss[i] == 'W' || ss[i] == 'G')){
            cout << "impossible" << endl;
            flag1 = 1;
            break;
          }
          else if(flag == 1 && ss[i] == 'W'){
            cout << "impossible" << endl;
            flag1 = 1;
            break;
          }
          else if(flag == 0 && ss[i] == 'R'){
            flag = 1;
          }
          else if(flag == 1 && ss[i] == 'G'){
            flag = 2;
            break;
          }
        }
        if(flag1 == 1){
          continue;
        }
        }
        int c = 0;
        int flag = 1;
        int index1 = 0;
        int index2 = 0;
        int index3 = 0;
        for(;;){
          if(index3==s.sz){
            flag = 0;
            break;
          }
          if(index1>index2||index2>index3){
            flag = 0;
            break;
          }
          if(s[index1]=='W'&&s[index2]=='G'&&s[index3]=='R'){
            c++;
            if(c==count(all(s),'G')&&c==count(all(s),'R')){
              break;
            }
            index1++;
            index2++;
            index3++;
          }
          else if(s[index3]!='R'){
            index3++;
          }
          else if(s[index2]!='G'){
            index2++;
          }
          else{
            index1++;
          }
        }
        if(flag == 0){
            cout << "impossible" << endl;
        }
        else{
            cout << "possible" << endl;
        }
    }
	return 0;
}