#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 a=0,b=0;
    rep(i,s.size()){
        if(s[i]=='W'){
            a++;
            continue;
        }
        if(s[i]=='G'){
            a--;
            b++;
            if(a<0){
                cout<<"impossible"<<endl;
                return;
            }
            continue;
        }
        if(s[i]=='R'){
            b--;
            if(b<0){
                cout<<"impossible"<<endl;
                return;
            }
        }
    }

    if(b||a==s.size())cout<<"impossible"<<endl;
    else cout<<"possible"<<endl;
}

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

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