def main():
    # Introduction
    print __doc__
 
    presVal = 1 # Set present value to $1
    intRate = input("Enter the Interest Rate >>") # Ask for the Interest Rate
    years = 0 # Start the years at zero
    futVal = presVal # Set the variable used to accumulate
 
    # Set the while loop
    while futVal <= presVal *2: # Continue 'while' futVal has not doubled
        futVal = futVal + futVal *((float(intRate)/100)) # Calc the next loop
        years = years + 1 # Add 1 to the years
 
    # Calculate the amount left of the part year
    fut = futVal%2
 
    # Print the answer   
    print            
    print "It takes approximately %0.2f years to double the present value" % (years-fut)