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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
 
 
public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		double b_int = Math.floor(b);
		double b_double = b-b_int;
		BigDecimal ans = new BigDecimal(a);
		BigDecimal b_int1 = new BigDecimal(b_int);
		BigDecimal b_double1 = new BigDecimal(b_double);
		ans = ans.multiply(b_int1);
		BigDecimal a_floor = new BigDecimal(a);
		a_floor = a_floor.multiply(b_double1);
		a_floor = a_floor.setScale(0, BigDecimal.ROUND_DOWN);
		ans = ans.add(a_floor);
		System.out.println(ans);
	 }
}