package mypackage;import java.math.BigInteger;import java.util.*;public class JieCheng { protected static ArrayList table = new ArrayList(); static {   table.add(BigInteger.valueOf(1)); } public static synchronized BigInteger factorial(int x){  if(x<0) throw new IllegalArgumentException("x must be non-negative");  for(int size = table.size();size<=x;size++){      BigInteger lastfact = (BigInteger)table.get(size-1);      BigInteger nextfact = lastfact.multiply(BigInteger.valueOf(size));      table.add(nextfact);      }      return (BigInteger) table.get(x);  }  public static void main(String args[]){      int i=60;      System.out.println(factorial(i));  }}