[RESOLVED] different answer

[vb_student]

Hello

i was tring to figure out what the result of factorial for 21 using the following code.

java code

import java.io.*;
/**
 *
 * @author  
 */
public class mywelcome {
  public static void main (String[] args) throws IOException
  {
    BufferedReader userin = new BufferedReader 
        (new InputStreamReader(System.in));
    String inputData;
    long    N, fact = 1; 

    System.out.println( "Enter N:" );
    inputData = userin.readLine();
    N         = Integer.parseInt( inputData );

    if ( N >= 0 )
    {
      while ( N > 1 )    
      {
        fact = fact * N;
        N    = N - 1;
      }
      System.out.println( "factorial is " + fact );
    }
    else
    {
      System.out.println("N must be zero or greater");
    }
  }
}

when i use the code in the netbeans environment, i get the answer -4249290049419214848
but the following link states the answer should be 51090942171709440000

http://chortle.ccsu.edu/CS151/Notes/...r+greater&N=20

can you guys tell me why the difference?