#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

string solve(string str){
    # define OK "possible"
    # define NG "impossible"
    int n = str.size(), w=0, g=0, r=0;
    bool running = false;
    reverse(str.begin(), str.end());
    if(str[0] != 'R') return NG;
    for(int i=0; i<n; ++i){
        char c = str[i];
             if(c == 'R') ++r;
        else if(c == 'G'){
            if(--r < 0) return NG;
            running = true;
            ++g;
        }
        else{
            ++w;
            if(!running) return NG;
            if(g>0) --g;
        }
    }
    if(r != 0 || g != 0) return NG;
    return OK;

}

int main(){
    int n;
    cin >> n;
    for(int i=0; i<n; ++i){
        string str;
        cin >> str;
        cout << solve(str) << endl;
    }
}