#include<bits/stdc++.h>
#define EM 1000000
using namespace std;
using LL = long long;
using P = pair<LL, LL>;
LL LINF = 1e18;
int INF = 1e9;
LL mod = 1e9+7;
using vint = vector<int>;
using vLL = vector<LL>;
using vvint = vector<vector<int>>;
using vvLL = vector<vector<LL>>;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

int main(){
    int T;
    cin >> T;
    for(int i = 0;i < T;i++){
        string s;
        cin >> s;
        bool ans = true;
        int w = 0, g = 0, r = 0, cnt = 2;
        for(int j = 0;j < s.size();j++){
            if(s[j] == 'W'){
                w++;
                cnt = 2;
            }else if(s[j] == 'G'){
                g++;
                if(g > w)   ans = false;
                if(cnt == 2)    cnt--;
            }else{
                r++;
                if(r > g)   ans = false;
                if(cnt == 1)    cnt--;
            }
        }
        if(r != g || g == 0 || cnt != 0)  ans = false;
        if(ans) cout << "possible" << endl;
        else    cout << "impossible" << endl;
    }
}