#pragma GCC optimize("O3")
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;

using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;

template <class T> inline T chmax(T &a, const T b) {return a = (a < b) ? b : a;}
template <class T> inline T chmin(T &a, const T b) {return a = (a > b) ? b : a;}

constexpr int MOD = 1e9 + 7;
constexpr int inf = 1e9;
constexpr long long INF = 1e18;
constexpr double pi = acos(-1);
constexpr double EPS = 1e-10;

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int t; cin>>t;
    while(t--){
        string s; cin>>s;
        int n = s.size();
        int wcnt = 0, gcnt = 0, rcnt = 0;

        bool valid = true;
        for(int i=n-1; i>=0; i--){
            if(s[i] == 'R'){
                rcnt++;
            }
            else if(s[i] == 'G'){
                if(0 < rcnt){
                    rcnt--;
                    gcnt++;
                }
                else{
                    valid = false;
                }
            }
            else{
                if(0 < gcnt){
                    gcnt--;
                    wcnt++;
                }
                else if(0 < wcnt){
                    wcnt++;
                }
                else{
                    valid = false;
                }
            }
        }

        if(!valid || rcnt != 0 || gcnt != 0) cout << "impossible" << endl;
        else cout << "possible" << endl;
    }
}