import std.stdio;
import std.string;
import std.conv;
import std.algorithm;
import std.range;
import std.array;
import std.typecons;
import std.random;

bool cityBus(string s, int[] routes = []){
  
  if(!s.length) return routes.reduce!min >= 3;
  auto tail = s.back.to!char;
  s = s[0..$-1];
  
  /// ***R --------------------------
  if(tail == 'R'){
    return cityBus(s, routes ~= 1);
  }
  /// ****G ------------------------
  else if(tail == 'G'){
    foreach(ref r; routes){
      if(r == 1){
        r += 1;
        return cityBus(s, routes);
      }
    }
    return false;
  }
  /// ***W -----------------------
  else{
    foreach(ref r; routes){
      if(r == 2){
        r += 1;
        return cityBus(s, routes);
      }
    }
    foreach(ref r; routes){
      if(r > 2){
        r += 1;
        return cityBus(s, routes);
      }
    }
    return false;
  }
}

void main(){
  immutable N = readln.strip.to!int;
  foreach(i; 0..N) writeln( cityBus(readln.strip) ? "possible" : "impossible" );
}