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: Accepted)

import java.util.*;
import java.math.*;
public class Main {
     public static String mul(String v1, String v2, int scale) {
        if (scale < 0) {
            throw new IllegalArgumentException(
                    "The scale must be a positive integer or zero");
        }
        BigDecimal b1 = new BigDecimal(v1);
        BigDecimal b2 = new BigDecimal(v2);
        return b1.multiply(b2).setScale(scale, BigDecimal.ROUND_DOWN).toString();
    }
    public static void main(String[] args)
    {
       Scanner input =new Scanner(System.in);
String str1=input.next();
        String str2=input.next();//会从控制5261台读入一4102个字符串，1653以空格版为标志权
        Main c=new Main();
        System.out.println(c.mul(str1,str2,0));

    }
}