Problem:
Score : 300 points

Problem Statement

Compute A \times B, truncate its fractional part, and print the result as an integer.

Constraints

0 \leq A \leq 10^{15}

0 \leq B < 10

A is an integer.

B is a number with two digits after the decimal point.

Input

Input is given from Standard Input in the following format:

A B

Output

Print the answer as an integer.

Sample Input 1

198 1.10

Sample Output 1

217

We have 198 \times 1.10 = 217.8. After truncating the fractional part, we have the answer: 217.

Sample Input 2

1 0.01

Sample Output 2

0

Sample Input 3

1000000000000000 9.99

Sample Output 3

9990000000000000

Solution in Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"
)

func main() {
	list := getStdinArr()
	N, _ := strconv.Atoi(list[0])
	M, _ := strconv.ParseFloat(list[1], 64)
	n := N
	m := int(math.Round(M * 100))
	fmt.Printf("%d\n", (n*m)/100)
}

var sc = bufio.NewReaderSize(os.Stdin, 1024*1024*1)

func getStdin() string {
	return readLine()
}
func getStdinArr() []string {
	str := getStdin()
	list := strings.Split(str, " ")
	return list
}
func readLine() string {
	buf := make([]byte, 0, 0)
	for {
		l, p, _ := sc.ReadLine()
		buf = append(buf, l...)
		if !p {
			break
		}
	}
	return string(buf)
}