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 Perl (5.26.1) (judge verdict: Accepted)

#!/usr/bin/perl
use Data::Dumper;
my ($a,$b) = split(/\s+/,<STDIN>);

my $mul = 0;
if( $b =~ /\./o ){
  my $x1 = $`;
  my $x2 = $';
  $mul = length($x2);
  $b = $x1 . $x2;
  $b =~ s/^0+//ios;
  $b = '0' unless length($b);
}

my $aa = '' . ( ($a-0) * ($b-0) );
if( $mul > 0 and length($aa)<( $mul + 1 ) ){
  $aa = ( '0' x ($mul + 1 -length($aa)) ) . $aa;
}

print (substr($aa,0,length($aa)-$mul) . "\n");