using System;

public class Program

{

    public static void Main()

    {

​

        // declare variables to be used

        double balance, interestRate, targetBalance; 

        Console.WriteLine("What is your current balance?"); 

        balance = Convert.ToDouble(Console.ReadLine()); 

        Console.WriteLine("What is your current annual interest rate (in %)?"); 

        interestRate = Convert.ToDouble(Console.ReadLine()) / 100.0; 

        Console.WriteLine("What balance would you like to have?"); 

        targetBalance = Convert.ToDouble(Console.ReadLine());

        // declare the counter

        int totalYears = 0; 

        do {

            // balance = balance + balance * interestRate;

            // balance = balance * (1 + interestRate);

            balance *= 1 + interestRate; 

            ++totalYears;

        } while (balance < targetBalance); 

        Console.WriteLine("In {0} year{1} you'll have a balance of {2}.", 

                          totalYears, 

                          (totalYears == 1 ? "": "s"), 

                          balance);

    }

}