/*
 * Parke Godfrey
 * 2009-10-21
 * Compute the difference between a list of fractions
 * and print the sum of the differences.
 */
import java.io.PrintStream;
import java.util.Scanner;
import type.lib.Fraction;

public class FractionDiff
{
    public static void main(String[] args)
    {
        PrintStream output = System.out;
        Scanner input = new Scanner(System.in);
        
        // Get the number of fractions to read in.
        output.println("Number of fractions to enter?");
        int numOfFrac = input.nextInt();
        
        // Read in the first fraction.
        output.println("Enter fraction #1 (numerator denominator):");
        Fraction before = new Fraction(input.nextLong(), input.nextLong());
        
        // Declare a fraction to accumulate the sum.
        // Should be "zero" to start.
        Fraction sum = new Fraction();
        
        // Read in subsequent fractions, computing the differences.
        for (int i = 2; i <= numOfFrac; i++)
        {
            output.println("Enter fraction #"
                    + i
                    + " (numerator denominator):");
            Fraction current = new Fraction(input.nextLong(),
                                            input.nextLong());
            
            // We do not use before again, so okay to subtract in-place.
            before.subtract(current);
            sum.add(before);

            output.println("The difference is " + before + ".");
            before = current; // Remember current now as previous one.
        }
        
        output.println("The sum of the differences is " + sum + ".");
    }
}