#include<bits/stdc++.h>
using namespace std;
main(){
    int t;
    string s;
    cin>>t;
    while(t--){
        cin>>s;
        int b=0;
        for(int i=0;i<s.length();++i){
            if(s[i]=='W')continue;
            b+=(s[i]=='G'?1:-1);
            if(b<0){cout<<"impossible\n";break;}
        }
        cout<<(b||s[s.length()-1]!='R'?"im":"")<<"possible\n";
    }
}