#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))
#define FOR(i, f, t)        for(int(i)=(f);(i)<(t);(++i))
#define RREP(i, n)          for(int(i)=(n)-1;(i)>=0;--(i))
const int MOD = int(1e9+7);

int N,M,W,H;
int res = 0;

bool solve(string &s){
    int n = s.size();
    REP(j,n){
        //cerr << s << endl;
        if(s[j] == 'R'){
            s[j] = '_';
            int k = j+1;
            bool f = false;
            for(;k<n;k++){
                if(s[k] == 'G'){ s[k] = '_', f = true; break; }
            }
            if(!f) return false;
            f = false;
            for(;k<n;k++){
                if(s[k] == 'W'){ s[k] = '_', f = true; break; }
            }
            if(!f) return false;

        }
        if(s[j] == 'G') return false;
    }
    return true;
}

int main(){
    do { cin.tie(0); ios_base::sync_with_stdio(false); } while(0);
    cin >> N;

    REP(i,N){
        string s; cin >> s;
        reverse(s.begin(), s.end());
        cout << (solve(s)?"possible":"impossible") << endl;
    }
    return 0;
}