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
// C
fscanf(STDIN, '%s %s', $a, $b);
$b1 = (int) ($b * 100);
$ans = (int) substr(omulti($a, $b1), 0, -2);
echo $ans;

function omulti($a, $b)
{
    $aa = str_split(strval($a));
    $bb = str_split(strval($b));
    foreach ($aa as $ka => $va) {
        foreach ($bb as $kb => $vb) {
            $res[$ka + $kb + 1] += intval($va) * intval($vb);
        }
    }
    for ($i = max(array_keys($res)); $i > 0; $i--) {
        if ($res[$i] > 9) {
            $res[$i - 1] += floor($res[$i] / 10);
            $res[$i] %= 10;
        }
    }
    ksort($res);
    return implode("", $res);
}