1.


/**
 * FWP, Ausgewählte Probleme aus dem ACM Programming Contest, SS10 
 * Problem: 10106 Product
 * Link: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=13&page=show_problem&problem=1047
 * 
 * @author Anton Pavlushko, IBB7B,  
 * @version 1.0, 10/10/2010
 * 
 * Status : Accepted
 * Runtime: 0.436
 */

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args) throws IOException {
	    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	    String current_line2, current_line, empty = "";
        int number, factorial, i, j, length, number_local, length_1, length_2, k;
        int primes [], counts [], current_multiply;
        double znak,count5,count5_already,multiply;
        StringTokenizer input_string;
        boolean status, at_least_one;
        int first[], second[], result[];
	    
	     try {
	         while ((current_line=in.readLine())!= null && !current_line.equals("0") &&
	        		 (current_line2=in.readLine())!= null) { 
	        	 current_line=current_line.trim();
	        	 current_line2=current_line2.trim();
	        	 
	        	 first = new int[251];
	        	 second = new int[251];
	        	 result = new int[502];
	        	 
	        	 length_1=current_line2.length();
	        	 for(i=length_1-1;i>=0;i--) {
	        		 second[length_1-i] = Integer.parseInt(current_line2.substring(i,i+1));
	        	 }
	        	 
	        	 length_2=current_line.length();
	        	 for(i=length_2-1;i>=0;i--) {
	        		 first[length_2-i] = Integer.parseInt(current_line.substring(i,i+1));
	        	 }
	        	 
	        	 if (!current_line.equals("0") && !current_line2.equals("0"))
	        	 for(i=1;i<=length_1;i++) {
	        		 
	        		 for(j=1;j<=length_2;j++) {
	        			 k=first[j]*second[i];
	        			 
		        		 result[i+j-1]+=k%10;
		        		 result[i+j]+=k/10;
		        		 
	        			 length=result.length;

	        			 do {
	        				 number=0;
	        			 for(k=0;k<length;k++) {
	        				 if (result[k]>=10) {
	        					 result[k+1]+=result[k]/10;
	        					 result[k]=result[k]%10;
	        					 number++;
	        				 }
	        			 }
	        			 } while (number>0);
	        		 }
	        	 }
	        	 
	        	 length=result.length;
	        	 empty="";
	        	 status=false;
	        	 for(i=length-1;i>0;i--) {
	        		 if (result[i]>0) status=true;
	        		 if (status) empty=empty+result[i];
	        	 }

	        	 if (current_line.equals("0") || current_line2.equals("0"))
		        	 System.out.println("0");
	        	 else
	        		 System.out.println(empty);
	         } // end while 
	       } // end try
	       catch (IOException e) {
	         System.err.println("Error: " + e);
	       }
	}
}


2. 

/**
 * ACM Training 2010 
 * ACM Problem #10106 - Product
 * Link: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=13&problem=1047&mosmsg=Submission+received+with+ID+7886373
 * 
 * @author Felix Dietrich
 * @version 1.0, 04/09/2010
 * 
 * Methode: BigInteger
 * Status : Accepted
 * Runtime: 0.144
 */

import java.math.BigInteger;
import java.util.*;

public class Main
{
	public static void main(String... strs)
	{
		Scanner sc = new Scanner(System.in);
		
		while(sc.hasNext())
		{
			BigInteger s1 = new BigInteger(sc.next());
			BigInteger s2 = new BigInteger(sc.next());
			
			System.out.println(s1.multiply(s2).toString());
		}
	}
}