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 Go (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"math/big"
	"os"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func main() {
	scanner.Split(bufio.ScanWords)

	const maxCapacity = 512 * 1024
	buf := make([]byte, maxCapacity)
	scanner.Buffer(buf, maxCapacity)

	aStr := nextString()
	bStr := nextString()

	a, _ := new(big.Int).SetString(aStr, 10)
	b, _ := new(big.Int).SetString(bStr, 10)
	c := big.NewInt(0).Mul(a, b)

	fmt.Println(c)
}