/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
import java.math.* ;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
 
    List< BigInteger > inputs =
        List.of( 
            new BigInteger( "3" ) , 
            new BigInteger( "7" ) , 
            new BigInteger( "10" ) , 
            new BigInteger( "2" ) 
        ) ;
 
    Optional< BigInteger > result = 
        inputs 
        .stream()
        .reduce( BigInteger :: multiply )
    ;
 
System.out.println( result ) ;
 
	}
}

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