How to Generate Alphanumeric Id using c# Linq

            var res = hrmsEntities.LeadGenerations.Select(x => x.LeadId.Substring(7)).ToList();

            int maxvalue = res.Select(int.Parse).DefaultIfEmpty(0).Max();

            int gen = Convert.ToInt32(maxvalue) + 1;

            var LeadId = "WRM/" + "LD" + "/" + gen;

            lvm.leadGeneration.LeadId = LeadId;