using System;
public class Program
{
public static void Main()
int g,sum=0,av,i ;
for(i=1;i<=5;i++)
Console.WriteLine("enter a grade");
g=int.Parse(Console.ReadLine());
while(g<0)
Console.WriteLine("enter a positive number");
sum=sum+g;
av=sum/5;
Console.WriteLine(" the avrage of the grades is {0}",av);
}