What's the service number of the Jammu Duronto train? 
CREATE TABLE "list_of_duronto_express_trains" (
  "service" real,
  "train_number" real,
  "train_name" text,
  "source" text,
  "departure" text,
  "destination" text,
  "arrival" text
);
SELECT MAX("service") FROM "list_of_duronto_express_trains" WHERE "train_name"='Jammu Duronto';