#include <iostream>
#include <string>
using namespace std;
int main()
{
  ios::sync_with_stdio(false);
  int T;
  string S;
  cin >> T;
  for( int i=0; i<T; i++ ){
    cin >> S;
    int d[3] = {0,0,0};
    bool f = true;
    for( int i=S.size()-1; i>=0; i-- ){
      switch( S[i] ){
        case 'R':
          d[0]++;
          break;
        case 'G':
          if( d[0] == 0 ){
            f = false;
          } else {
            d[0]--;
            d[1]++;
          }
          break;
        case 'W':
          if( d[1] > 0 ){
            d[1]--;
            d[2]++;
          } else if( d[2] == 0 ) {
            f = false;
          }
          break;
      }
      if( !f ) break;
    }
    if( f ) cout << "possible" << endl;
    else cout << "impossible" << endl;
  }
}