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​

using System;

​

public class HelloWorld

{

    public static string Xyz(int x, int y){

        int sum = x + y;

        string Ans = "the sum of " + x + " and y " + y + " sum " + sum;

        return Ans;

    }

    public static string stringConc(string x, string y){

        string sep = " ";

        string Ans = x + sep + y;

        return Ans;

    }

    public static void Main(string[] args)

    {

        Console.WriteLine(Xyz(20,30));

        Console.Write("Enter an interger: ");

        var stringaNumber = Console.ReadLine();

        int a;

        bool isNumber = int.TryParse(stringaNumber, out a);

        Console.Write("Enter an second interger: ");

        var stringbNumber = Console.ReadLine();

        int b;

        bool isbNumber = int.TryParse(stringbNumber, out b);

        if(isNumber && isbNumber){

            Console.WriteLine(Xyz(a,b));

        } else if(!isNumber && !isbNumber){

            Console.WriteLine(stringConc(stringaNumber,stringbNumber));

        } else {

            Console.Write("You canno't sum or concat one integer and one string");

        }

    }

}