Answer:   You can create a console application in this case with below logic –
using System;
namespace Demo
{
class Program
{
static void Main(string[] args)
{
string input = string.Empty;
Console.WriteLine("Enter your input”);
input = Console.ReadLine();
if(input.ToLower() == “yes”)
Console.WriteLine(“no”);
else if(input.ToLower() == “no”)
Console.WriteLine(“yes”);
else
Console.WriteLine(“invalid input”);
}
}
}