Problem:
Multiplication of Big Integers II

Given two integers $A$ and $B$, compute the product, $A \times B$.

Input

Two integers $A$ and $B$ separated by a space character are given in a line.

Output

Print the product in a line.

Constraints

$-1 \times 10^{200000} \leq A, B \leq 10^{200000}$

Sample Input 1

5 8

Sample Output 1

40

Sample Input 2

100 25

Sample Output 2

2500

Sample Input 3

-1 0

Sample Output 3

0

Sample Input 4

12 -3

Sample Output 4

-36

Solution in C# (judge verdict: Time Limit Exceeded)

#pragma warning disable

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Numerics;
using System.Collections;
using System.Timers;

static class MainClass
{
    public static void Main(string[] args)
    {
        var ab = Console.ReadLine().SplittedStringToBigInteger();
        Console.WriteLine(ab[0] * ab[1]);
    }
    #region ライブラリ
    public static long ToInt64(this string str) => long.Parse(str);
    public static int ToInt32(this string str) => int.Parse(str);
    public static BigInteger ToBigInteger(this string str) => BigInteger.Parse(str);
    public static List<string> SplittedStringToList(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
    public static List<int> SplittedStringToInt32List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToList();
    public static List<BigInteger> SplittedStringToBigInteger(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => BigInteger.Parse(x)).ToList();

    public const int INF = int.MaxValue / 2;
    #endregion
}