#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;

int main(){

    int T, g;
    string S;
    cin >> T;

    while(T){
        cin >> S;
        g = 0;
        if (S.back() != 'R'){
            cout << "impossible" << endl;
            T--;
            continue;
        }

        for (int i=0; i<S.size(); i++){
            if (S[i] == 'G') g++;
            else if (S[i] == 'R'){
                if (g == 0){
                    T--;
                    cout << "impossible" << endl;
                    continue;
                }
                else g--;
            }
        }
        cout << (g == 0 ? "possible" : "impossible") << endl;
        T--;
    }

    return 0;
}