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 Kotlin (1.3.71) (judge verdict: Accepted)

import java.math.BigDecimal

fun main() = Thread(null, ::abc169c, "(^o^)", 128 * 1024 * 1024).apply { start() }.join()

@OptIn(ExperimentalStdlibApi::class)
fun abc169c() {
    val (a, b) = readLine()!!.split(' ').map { it.toDouble() }

    val answer = BigDecimal.valueOf(a).multiply(BigDecimal.valueOf(b)).toLong()

    println(answer)
}