#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>

#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
typedef long long ll;

using namespace std;


int inputValue(){
    int a;
    cin >> a;
    return a;
};

template <typename T>
void output(T a, int precision) {
    if(precision > 0){
        cout << setprecision(precision)  << a << "\n";
    }
    else{
        cout << a << "\n";
    }
}

int main() {
    
    // source code
    
    int N = inputValue();
    
    rep(i, N){
        string s;
        cin >> s;
        
        bool pos = true;
        
        bool wflag = false;
        int check = 0;
        int w = 0;
        int g = 0;
        int r = 0;
        
        rep(j, s.size() - 1){
            if (s[j] == 'W') {
                w++;
                wflag = true;
            }
            else if (s[j] == 'G'){
                g++;
                check++;
                wflag = false;
            }
            else{
                r++;
                check--;
                if (check < 0) {
                    pos = false;
                    break;
                }
            }
        }
        
        if (s[s.size() - 1] != 'R') {
            pos = false;
        }
        else{
            r++;
            check--;
            if (g != r || w < r || check != 0 || wflag) {
                pos = false;
            }
        }
        output(pos ? "possible" : "impossible", 0);
        
    }
    
    return 0;
}