import java.util.*;
public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    }
} Main public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    } main {
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc long b = (long)(sc.nextDouble() * 100 + 0.01); b (long)(sc.nextDouble() * 100 + 0.01) sc.nextDouble() * 100 sc.nextDouble() sc.nextDouble sc 100 0.01 long ans = a * b; ans a * b a b System.out.print(ans / 100) System.out.print System.out System System.out ans / 100 ans 100 String[] args args public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    }
} public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    }
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      long a = sc.nextLong();
      long b = (long)(sc.nextDouble() * 100 + 0.01);
      long ans = a * b;
      System.out.print(ans / 100);
    }
}
