Set ArrayList exercise practice--score

Namespace set exercises to practise a practice
{
Class Program
{
static void Main (string[] args)
{
Console.WriteLine ("Please Enter your class number:");
int n = Convert.ToInt32 (Console.ReadLine ());
ArrayList al = new ArrayList ();
for (int i = 0; i < n; i++)
{
Console.WriteLine ("The" + (i+1) + "The results of the students are:");
Al. ADD (Convert.ToInt32 (Console.ReadLine ()));
}
for (int i = 0; i < al. Count; i++)
{
Console.WriteLine ("The students ' grades are" +al[i]+ ");
}
Double sum = 0;

for (int i = 0; i < n; i++)
{
sum = sum + convert.toint32 (al[i]);
}
Console.WriteLine ("The total score is" +sum+ ");
Al. Sort ();
for (int i = 0; i < al. Count; i++)
{
Console.WriteLine ("Students ' grades are arranged in a certain order as" + Al[i] + "points");
}
Double Ave = 0;
Ave = (Sum-convert.toint32 (al[0])-Convert.ToInt32 (Al[4])/(AL. COUNT-2);
Console.WriteLine ("The average of your class is divided into" +ave+ ");

Console.ReadLine ();
}
}
}

Set ArrayList exercise practice--score