proyect euler 40

public class problem40 
{
 public static void main(String[] args) 
 {
  StringBuffer a = new StringBuffer();
  a.append("123456789");
  int n =1;
  while(n<=100000)
  {
   for(int i = 0; i <=9; i++) 
   {
    String elem = Integer.toString(n)+Integer.toString(i);
    a.append(elem); 
   }
   n++;
  }
  int p =1;
  int c =1;
  for (int i = 0; i <= 6; i++) 
  {
       c=c*(a.charAt(p-1)-48);
       p=p*10;
  }
  System.out.println(c);
 }
}