/*********************************************************************
Write a loan calculator program. The user borrows A dollars at R%
interest (compounded monthly) and makes a payment of P dollars at the
end of each month. Your program should get all of this information
from the user as well as Y, a number of years to simulate, and should
return the balance left after Y years. A typical run of the program
might look something like this:

Enter the amount borrowed: 10000
Enter the monthly payment you'll make: 200
Enter the annual interest rate: 7.5
Enter the number of years you want to simulate: 3
At the end of 3 years you owe 4468.19 dollars

By running the program several times, you should be able to tell me
approximately how long it'll take to pay off your debt.

For those that are unfamiliar with annual rates compounded monthly, if
R is the given annual rate and we do monthly compounding, then each
month's interest is computed at the rate R/12. Remember, if your
balance owed at the beginning of the month is b then your balance owed
at the end of the month will b(1 + (R/100)/12) minus the payment P you
make at the end of the month. 
***********************************************************************/

#include <iostream>

using namespace std;

int main()
{
  double a, m, r;
  int y, I;

  // Input amount, payment, interest rate, and number of years
  cout << "Enter the amount borrowed: ";
  cin >> a;
  cout << "Enter the monthly payment you'll make: ";
  cin >> m;
  cout << "Enter the annual interest rate: ";
  cin >> r;
  cout << "Enter the number of years you want to simulate: ";
  cin >> y;

  // convert interest rate from percent to fraction
  r = r/100;

  // iterate through each month
  for(int i = 0; i < y*12; i++)
  {
    // calculate additional interest
    I = a*(r/12);
    // add interest and subtract payment from balance
    a = a + I - m;
  }

  // Print ending amount
  cout << "At the end of " << y << " years you owe "
       << a << " dollars" << endl;

  return 0;
}