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: Wrong Answer)

package main

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

func main() {
	var a int
	var b float64
	fmt.Scanf("%d %f", &a, &b)

	intB := int(math.Floor(b * 100))
	fmt.Printf("%d\n", (a*intB)/100)
}

func scanLongIntSlices(lines int, maxBufSize int) ([][]int, error) {

	res := [][]int{}

	sc := bufio.NewScanner(os.Stdin)
	buf := make([]byte, bufio.MaxScanTokenSize)
	sc.Buffer(buf, maxBufSize)

	for sc.Scan() {
		line := sc.Text()
		strs := strings.Split(line, " ")
		ints := make([]int, len(strs))
		for i, c := range strs {
			n, err := strconv.Atoi(c)
			if err != nil {
				return nil, err
			}
			ints[i] = n
		}
		res = append(res, ints)
	}

	if err := sc.Err(); err != nil {
		return nil, err
	}

	return res, nil
}