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