#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

#define FORR(i,b,e) for(int i=(b);i<(int)(e);++i)
#define FOR(i,e) FORR(i,0,e)
#define sortuniq(v) sort(v.begin(), v.end()), v.erase(unique(v.begin(),v.end()),v.end())
#define dump(var) cerr << #var ": " << var << "\n"
#define dumpc(con) for(auto& e: con) cerr << e << " "; cerr<<"\n"

typedef long long ll;
typedef unsigned long long ull;

const double EPS = 1e-6;
const int d4[] = {0, -1, 0, 1, 0};

using namespace std;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int T;
    cin >> T;
    while (T--) {
        string S;
        cin >> S;
        int gr = 0;
        bool possible = true;
        for (auto &c: S) {
            if (c == 'G') {
                gr++;
            }
            else if (c == 'R') {
                gr--;
                if (gr < 0) {
                    possible = false;
                    break;
                }
            }
        }
        if (gr > 0 || S.back() != 'R') possible = false;
        cout << (possible? "possible": "impossible") << '\n';
    }
    
    return 0;
}