#include "bits/stdc++.h"
#define REP(i,n,N) for(ll i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LLINF = 1e18;

int main(){
    int T;
    string s;
    cin>>T;
    REP(i,0,T) {
        cin >> s;
        int G = 0, W = 0;
        bool flag = false;
        REP(i, 0, s.size()) {
            if (s[i] == 'G') {
                if (W > 0) {
                    G++;
                    W--;
                    flag = true;
                } else {
                    flag = false;
                    break;
                }
            } else if (s[i] == 'R') {
                if (G) G--;
                else {
                    flag = false;
                    break;
                }
            } else {
                W++;
                flag = false;
            }
        }
        if (G == 0 && flag) p("possible");
        else p("impossible");
    }
    return 0;
}