Как найти наибольшее значение в каждой группе с использованием LINQ ?

class Employees
{
    public int EmpId { get; set; }
    public int DeptId { get; set; }
    public int Salary { get; set; }
}

List<Employees> emp = new List<Employees>();
// populate emp 
// emp.Add(new Employees() { EmpId = 1, DeptId = 1, Salary = 20000 });

var highest = from e in emp
            group e by e.DeptId into dptgrp
              let topsal = dptgrp.Max(x => x.salary)
            select new
            {
                Dept = dptgrp.Key,
                TopSal = dptgrp.First(y => y.Salary == topsal).EmpId,
                MaximumSalary = topsal
            };

let topsal = dptgrp.Max(x => x.salary)

TopSal = dptgrp.First(y => y.Salary == topsal).EmpId