#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1e9+7;

main(){  
    int N;
    cin >> N;
    for(int i = 0;i < N;i++){
        string S;
        cin >> S;
        //reverse(S.begin(),S.end());
        int rcnt = 0,gcnt = 0,wcnt = 0;
        bool ng = 0;
        for(char c:S){
            if(c == 'R')rcnt++;
            if(c == 'G')gcnt++;
            if(c == 'W')wcnt++;
            //GR列が対応してない
            if(gcnt < rcnt){ng = 1;break;}
            //全ての'G'に対して'W'が一つ以上ない
            if(gcnt > wcnt){ng = 1;break;}
            //if(c == 'W' && (rcnt == 0 || gcnt == 0)){ng = 1;break;}
        }
        //最後の{G,R}の後ろにWが存在する
        for(int i = S.size() - 1;i >= 0;i--){
            if(S[i] == 'W'){ng = 1;break;}
            if(S[i] == 'G')break;
        }
        if(gcnt != rcnt)ng = 1;
        if(ng)cout << "impossible" << endl;
        else cout << "possible" << endl;
    }
}