#include <iostream>
#include <algorithm>
using namespace std;
int main(){
    int t;cin>>t;
    while(t--){
        string s;cin>>s;
        reverse(s.begin(),s.end());
        int nw = 0;
        bool ok = false;
        bool ans = true;
        for(int i = 0; s.size() > i; i++){
            if(s[i] == 'R')nw++;
            else if(s[i] == 'G'){
                nw--;
                ok = true;
                if(nw < 0){
                    ans = false;
                    break;
                }
            }else{
                if(!ok){
                    ans = false;
                    break;
                }
            }
        }
        cout << (ans?"possible":"impossible") << endl;
    }
}