My code below is failing at test 5. Please help me.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;

public class Cryptography1086
{
    public static void main( String[] args ) throws Exception
    {
        BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );

        StringTokenizer st = new StringTokenizer( br.readLine() );

        int numberOfNails = Integer.parseInt( st.nextToken() );

        double radiusOfNails = Double.parseDouble( st.nextToken() );

        double lengthOfRope = 2 * Math.PI * radiusOfNails;

        st = new StringTokenizer( br.readLine() );
        double x0 = Double.parseDouble( st.nextToken() );
        double y0 = Double.parseDouble( st.nextToken() );

        if( numberOfNails == 1 )
        {
            DecimalFormat df = new DecimalFormat( "#.00" );

            System.out.println( df.format( lengthOfRope ) );
            return;
        }

        double xStore = x0;
        double yStore = y0;

        double xK = 0;
        double yK = 0;

        for( int inx = 1 ; inx < numberOfNails; ++inx )
        {
            st = new StringTokenizer( br.readLine() );

            xK = Double.parseDouble( st.nextToken() );
            yK = Double.parseDouble( st.nextToken() );

            double dx = Math.pow( (xK - x0), 2 );
            double dy = Math.pow( (yK - y0), 2 );

            double dxy = Math.sqrt( dx + dy );

            lengthOfRope += dxy;

            x0 = xK;
            y0 = yK;
        }

        double d1 = Math.pow( (xK - xStore), 2 );
        double d2 = Math.pow( (yK - yStore), 2 );
        lengthOfRope += Math.sqrt( d1 + d2 );


        DecimalFormat df = new DecimalFormat( "#.00" );

        System.out.println( df.format( lengthOfRope ) );
    }
}

The problem was my usage of DecimalFormat df = new DecimalFormat( "#.00" );

It should have been something like this: DecimalFormat df = new DecimalFormat( "0.00" );

Note the '#' to '0' change.

You are correct, but what is the difference between the two thing?