#include<bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,a,b) for(int i=(a);i<(b);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
typedef vector<int>vi;

void solve(){
    string s;cin>>s;

    int r=0,g=0,w=0,latte=0;
    for(int i=s.size()-1;i>=0;i--){
        if(s[i]=='R')r++;
        if(s[i]=='G')g++;
        if(s[i]=='W'){
            latte=min(latte+1,g);
            w++;
        }

        if(r<g){
            cout<<"impossible"<<endl;
            return;
        }
        if(w&&(r==0||g==0)){
            cout<<"impossible"<<endl;
            return;
        }
    }

    if(r==g&&g==latte&&r)cout<<"possible"<<endl;
    else cout<<"impossible"<<endl;
}

signed main(){
    int N;
    cin>>N;

    while(N--)solve();
    return 0;
}