using System;

​

public class Program

{

    public static void Main()

    {   

        //If you have several statements that you want to check, you can make a checked block like below: 

        long a = 9999999999;

        long b = long.MaxValue;

​

        checked

        {

            int a1 = (int)a; // OverflowException

            int b1 = (int)b; // OverflowException

        }

​

​

    }

}