using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter a sentence:");

        string sentence = Console.ReadLine();

        Console.WriteLine("Enter the word to replace:");

        string oldWord = Console.ReadLine();

        Console.WriteLine("Enter the replacement word:");

        string newWord = Console.ReadLine();

        // Replace occurrences of the old word with the new word

        string updatedSentence = sentence.Replace(oldWord, newWord);

        // Using string concatenation for output

        Console.WriteLine("Updated sentence: " + updatedSentence);

    }

}

​

​