#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
using lint=long long;
using lubl=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint q;std::cin>>q;
    while(q--){
        std::string s;std::cin>>s;
        lint r=0,g=0,w=0;
        bool ng=false;
        for(char c:std::string(s.rbegin(),s.rend())){
            (c=='R'?r:c=='G'?g:w)++;
            ng|=r<g||!g&&w;
            if(g<w)w=g;
        }
        ng|=r!=g||w!=g;
        std::cout<<(ng?"impossible":"possible")<<'\n';
    }
}