#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;
        for(char c:S){
            if(rcnt < gcnt)break;
            if(c == 'R')rcnt++;
            if(c == 'G')gcnt++;
            if(c == 'W' && (rcnt == 0 || gcnt == 0)){rcnt = -1;break;}
        }
        if(rcnt != gcnt || S.length() < 3)cout << "impossible" << endl;
        else cout << "possible" << endl;
    }
}