#include <iostream>
#include <string>
using namespace std;

void solve(){
    string s;cin>>s;
    int g=0,r=0,gr=0;
    int N=s.size();
    for(int i=0;i<N;i++){
        if(s[i]=='G'){
            g++;
            gr++;
        }
        if(s[i]=='R'){
            r++;
            gr--;
        }
        if(gr<0){
            cout << "impossible" <<endl;
            return;
        }
    }
    if(g!=r||g==0||r==0||s[N-1]!='R'){
        cout << "impossible" <<endl;
        return;
    }
    for(int i=N-1;i>=0;i--){
        if(s[i]=='G') break;
        if(s[i]=='W'){
            cout << "impossible" << endl;
            return;
        }
    }
    int cnt=0;
    for(int i=0;i<N;i++){
        if(s[i]=='W') cnt++;
        if(s[i]=='G') cnt--;
        if(cnt<0){
            cout << "impossible" << endl;
            return;
        }
    }
    cout << "possible" << endl;
}

int main(){
    int T;
    cin>>T;
    for(int i=0;i<T;i++){
        solve();
    }
}