#include <bits/stdc++.h>

using namespace std;

int T, N;
string S;

bool rec(int number = 0){
    
    if(number == N) return true;
    
    int r = 0, g = 0, w = 0;
    int flag = false;
    
    if((r = S.rfind("R")) != string::npos && S.find("G", r) == string::npos && S.find("W", r) == string::npos){
        if((g = S.rfind("G", r)) != string::npos && S.find("W", g) == string::npos){
            if((w = S.rfind("W", g)) != string::npos){
                S[r] = S[g] = S[w] = 'A';
                flag = rec(number + 1);
            }
        }
    }
    
    return flag;
}

int main(void){
    
    cin >> T;
    
    int i, j, k, p;
    for(i = 0; i < T; ++i){
        cin >> S;
        
        j = k = p = 0;
        while((p = S.find("G", p)) != string::npos && p <= S.size()){
            ++j;
            ++p;
        }
        p = 0;
        while((p = S.find("R", p)) != string::npos && p <= S.size()){
            ++k;
            ++p;
        }
        
        if(j != k){
            cout << "impossible" << endl;
        }
        else{
            N = j;
            if(rec()){
                cout << "possible" << endl;
            }
            else cout << "impossible" << endl;
        }
        
    }
    
    return 0;
}