#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();
    int w, g, r, lw, lg, lr;
    w=g=r=0;
    lw=lg=lr = -1;
    REP(j,n){
        switch(s[j]){
        case 'W':
            w++;lw=j;
            break;
        case 'G':
            if(w == 0) return false;
            w--;g++;lg=j;
            break;
        case 'R':
            if(g == 0) return false;
            g--;r++;lr=j;
            break;
        }
    }
    if(g != 0 || r == 0) return false;
    if(lw < lg && lg < lr) return true;
    return false;
}


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

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