using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        // Student collection

        List<Student> studentList = new List<Student>() { 

                new Student() { StudentID = 1, StudentName = "John", Age = 13} ,

                new Student() { StudentID = 2, StudentName = "Moin",  Age = 21 } ,

                new Student() { StudentID = 3, StudentName = "Bill",  Age = 18 } ,

                new Student() { StudentID = 4, StudentName = "Ram" , Age = 20} ,

                new Student() { StudentID = 5, StudentName = "Ron" , Age = 15 } 

            };

        // Student collection

        List<Permission> permissionsList = new List<Permission>() { 

                new Permission() { StudentID = 1, PermissionID = 1, PermissionName = "PermissionName1", HasPermission = true} ,

                new Permission() { StudentID = 1, PermissionID = 2, PermissionName = "PermissionName2",  HasPermission = false } ,

                new Permission() { StudentID = 2, PermissionID = 1, PermissionName = "PermissionName1", HasPermission = true} ,

                new Permission() { StudentID = 2, PermissionID = 2, PermissionName = "PermissionName2",  HasPermission = false } ,

                new Permission() { StudentID = 3, PermissionID = 1, PermissionName = "PermissionName1", HasPermission = true} ,

                new Permission() { StudentID = 4, PermissionID = 2, PermissionName = "PermissionName2",  HasPermission = false } ,

            };

        studentList.ForEach(s => s.Permissions = new List<Permission>(permissionsList.Where(p => p.StudentID == s.StudentID)));

        foreach(Student s in studentList){          

            Console.WriteLine(string.Concat(s.StudentName, s.Permissions.Count().ToString()));

        }

    }

}

​

public class Student{

​

    public int StudentID { get; set; }

    public string StudentName { get; set; }

    public int Age { get; set; }

    public IList<Permission> Permissions { get; set; }

}

​

public class Permission{

​

    public int StudentID { get; set; }

    public int PermissionID { get; set; }

    public string PermissionName { get; set; }

    public bool HasPermission { get; set; }

}