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

int main()
{
    int T; cin>>T;
    while (T--) {
        string s; cin>>s;
        int n=s.size();

        const string possible="possible";
        const string impossible="impossible";

        string res=possible;
        vector<string> bus;
        for(int i=n-1; i>=0; --i) {
            char c=s[i];
            if (c=='R') {
                bus.push_back("R");
            }
            else if (c=='G') {
                bool ok=false;
                for(auto& b: bus) if (b.back()=='R') { b+=c; ok=true; break; }
                if (!ok) res=impossible;
            }
            else {
                bool ok=false;
                for(auto& b: bus) if (b.back()=='G') { b+=c; ok=true; break; }
                if (!ok) {
                    for(auto& b: bus) if (b.back()=='W') { ok=true; break; }
                }
                if (!ok) res=impossible;
            }
        }
        for(auto& b: bus) if (b!="RGW") res=impossible;
        cout<<res<<endl;
    }
}