Hi, all ,what is the problem in my code?

I am solving a travelling saleman problem ,
and now I am using the test data named " oliver30"
but I can not get the right path length .
I was supposed to get about 423.74 as the minimum path length ...

import java.applet.Applet;
import java.math.*;
import java.util.*;
import java.awt.Graphics;
import java.io.*;
public class tspPrint extends Applet{
    public void paint(Graphics g)
    {
        try{
            Scanner cin = new Scanner( new FileInputStream("input1.txt"));
            int n = cin.nextInt();

        BufferedReader f2 =
            new BufferedReader(
                new InputStreamReader(new
FileInputStream("input2.txt")));
        int [] a = new int [n];
        double []x = new double[n];
        double [] y = new double[n];
        int temp = 0;
        for( int i = 0 ;i< n ;i++)
        {
            temp = cin.nextInt();
            x[i] =50* cin.nextDouble();

            y[i] =50 * cin.nextDouble();
            temp = cin.nextInt();
        }
        String Line = f2.readLine();
        StringTokenizer st = new StringTokenizer(Line);
        for(int i = 0 ;i< n ;i++ )
        {
            a[i] = Integer.parseInt(st.nextToken());
        }
        for(int i = 0 ;i< n-1; i++)
        {
            g.drawLine((int)x[a[i]],(int)y[a[i]],(int)x[a[i+1]],(int)y[a[i
+1]]);
        }
        g.drawLine((int)x[a[0]],(int)y[a[0]],(int)x[a[n-1]],(int)y[a[n-1]]);

        // problem here
        // s should be about
423.74 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        //s: get the path
Length !!!!!
        //y?
        double s = 0 ;
        double dx = x[a[0]] -x[a[n-1]];
        double dy = y[a[0]] - y [a[n-1]];
        s += Math.sqrt(dx*dx + dy* dy);
        for( int i = 0 ;i< n -1 ;i++ )
        {
             dx = x[a[i]] - x[a[i+1]];
             dy = y[a[i]] - y[a[i+1]];
            s+= Math.sqrt( dx*dx + dy*dy);
        }

        g.drawString(Double.toString(s),5,35);

        }catch(Exception e)
        { System.out.println(e.toString());}
    }
}