Function with lookup field to update a field

Function with lookup field to update a field

Hi,
I want to update the name of a record based on 2 lookup field in this record.
It's working : I have a workflow with this function :

  1. resp = zoho.crm.getRecordById("Referencement_expert",Referencement_expert_ID);
  2. Er = resp.get("Expert_refere");
  3. Cr = resp.get("Contact_a_qui_on_refere");

  5. // Create the new Name field value
  6. name = Er + " - " + Cr;

  8. // Update the record with the new Name value
  9. mp = Map();
  10. mp.put("Name",name);
  11. update = zoho.crm.updateRecord("Referencement_expert",Referencement_expert_ID,mp);
  12. info update;


My problem seems to be with the lookup field.
Zoho return something as a Json so it return everything. 
Exemple : 
I want to have: "John Doe - Jo Moe",
I get
{"name":"John Doe","id":"499867000023328784"} - {"name":"Jo Moe","id":"49986700002332659"} in my name field.

How can it return only the name like in my example?
Thanks