#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false), cin.tie(nullptr);
    int T; cin >> T;

    while(T--){
        string S; cin >> S;

        int cr = 0, cg = 0, cw = 0;
        bool ok = true;
        reverse(S.begin(), S.end());
        for(auto c : S){
            if(c=='R') cr++;
            else if(c=='G'){
                if(cr==0) ok = false;
                else cr--, cg++;
            }
            else{
                if(cg==0 and cw == 0) ok = false;
                else if(cg) cg--, cw++;
            }
        }
        
        if(cr or cg) ok = false;
        
        if(ok) cout << "possible" << endl;
        else cout << "impossible" << endl;
    }
    
    return 0;
}