List<Student> list = ....;
list[0]  = {id = 1, name = "aa", ListMinute = List<String> ls1}
list[1]  = {id = 2, name = "bb", ListMinute = List<String> ls2}
list[2]  = {id = 3, name = "cc", ListMinute = List<String> ls3}
list[3]  = {id = 4, name = "dd", ListMinute = List<String> ls4}

List<String> ls1 = {"120", "150", "45", "195"}; //List in minutes.

List<String> ls1 = {"2", "2.30", "0.45", "3.15"}; // List in hours and minutes.