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 PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
list($a,$b)=explode(" ",trim(fgets(STDIN)));
$x=(int)$a;
$y=(int)($b*1000);
$ans=(int)($x*$y);
$n=strlen($ans);
if($n<4){
  echo 0;
  exit;
}
echo substr($ans,0,$n-3);