#include <bits/stdc++.h>
using namespace std;
int t;
char s[1010];
int main(){
    cin>>t;
    for(int k=0;k<t;++k){
        cin>>s;
        int len=strlen(s),w=0,wc=0,gc=0,i;
        for(i=len-1;i>=0;--i){
            if(s[i]=='G'&&!gc||s[i]=='W'&&!w)
                break;
            if(s[i]=='R') ++gc;
            if(s[i]=='G') --gc,++wc,w=1;
            if(s[i]=='W'){
                if(wc) --wc;
                w=1;
            }
        }
        if(i>=0||wc||gc)
            cout<<"impossible"<<endl;
        else
            cout<<"possible"<<endl;
    }
    return 0;
}