"""File:     simple_int.py
   Purpose:  Compute the amount of a principal given a simple interest
             rate and the time in years

   Run:      python simple_int.py

   Input:    Principal (decimal fraction)
             Interest rate (decimal fraction)
             Time in years (decimal fraction)
   Output:   The amount
"""

#----------------------------------------------------------------------
def simple_int(P, r, t):
   """ Find the amount of a principal P invest for t years at
   interest rate r.
   """
   A = P*(1+r*t)
   return A


#----------------------------------------------------------------------
# Program starts executing here
P = float(raw_input("Enter the principal\n"))
r = float(raw_input("Enter the interest rate (decimal fraction)\n"))
t = float(raw_input("Enter the time in years (decimal fraction)\n"))

A = simple_int(P, r, t)
print "If", P, "dollars is invested for", t, "years at interest rate", r
print "  then the amount will be", A, "dollars"