#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main()
{
    int T; cin>>T;
    while (T--) {
        string s; cin>>s;
        int n=s.size();
        vector<int> v;
        bool possible=true;
        for(int i=n-1;i>=0;--i) {
            if (s[i]=='R') {
                v.push_back(1);
            }
            if (s[i]=='G') {
                auto k=find(begin(v), end(v), 1);
                if (k==end(v)) { possible=false; break; }
                *k|=2;
            }
            if (s[i]=='W') {
                auto k=find(begin(v), end(v), 3);
                if (k!=end(v)) { *k|=4; }
                else {
                    k=find(begin(v), end(v), 7);
                    if (k==end(v)) { possible=false; break; }
                }
            }
        }
        for(int a: v) if (a!=7) { possible=false; break; }
        cout<<(possible?"possible":"impossible")<<endl;
    }
}