#include <iostream>
#include <ginac/ginac.h>
using namespace std;
using namespace GiNaC;



int main (){

  symbol j_sym("j");
  symbol n("n");
  idx j(j_sym,n);
  symbol S("S");

  try {
    ex e("2*S.j+n", lst(S,j,n));
    cout << "ok! :" << e << endl;
  } catch (exception &p) {
    cerr << p.what() << endl;
  }
}