#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

int main()
{
    int T; cin>>T;
    while (T--) {
        string s; cin>>s;
        reverse(begin(s), end(s));

        bool res=true;
        vector<int> a;
        for(auto& c: s) {
            if (c=='R') {
                a.push_back(0);
            }
            else if (c=='G') {
                auto t=find(begin(a), end(a), 0);
                if (t==end(a)) {
                    res=false;
                    break;
                }
                *t=1;
            }
            else if (c=='W') {
                auto t=find(begin(a), end(a), 1);
                if (t==end(a) and find(begin(a), end(a), 2)==end(a)) {
                    res=false;
                    break;
                }
                *t=2;
            }
        }
        if (count(begin(a), end(a), 2)!=a.size()) res=false;

        cout<<(res ? "possible" : "impossible")<<endl;
    }
}