# This program prompts for information about a
# loan and computes the monthly mortgage payment.
# This version is decomposed into functions.

# Obtains and returns needed values from the user.
def read_input():
    print("Monthly Mortgage Payment Calculator")
    loan = float(input("Loan amount? "))
    years = int(input("Number of years? "))
    rate = float(input("Interest rate? "))
    print()
    return loan, years, rate

# Computes and returns the monthly payment for a
# loan with the given values.
def compute_payment(loan, years, rate):
    # compute payment result
    n = 12 * years
    c = rate / 12.0 / 100.0
    payment = loan * c * (1 + c) ** n / ((1 + c) ** n - 1)
    return payment

def main():
    # compute payment and report result to user
    loan, years, rate = read_input()
    payment = compute_payment(loan, years, rate)
    print("Monthly payment is: $", round(payment, 2))

main()