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 Ruby (2.7.1) (judge verdict: Runtime Error)

a, b = gets.split
a = a.chars.map(&:to_i)
b = ((b.to_f)*100).to_i.to_s.chars.map(&:to_i)
ans = Array.new(a.size + 3, 0)
a.size.times do |i| 3.times do |j|
  ans[i + j + 1] += a[i] * b[j]
end end
(ans.size - 1).downto(1) do |i|
  ans[i - 1] += ans[i] / 10
  ans[i] = ans[i] % 10
end
puts ans.join.to_i / 100