#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; }