import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc double b = sc.nextDouble(); b sc.nextDouble() sc.nextDouble sc long bb = (long)((double)100 * b + 0.1); bb (long)((double)100 * b + 0.1) (double)100 * b (double)100 b 0.1 long ans = (a * bb) / (long)100; ans (a * bb) / (long)100 (a * bb) a bb (long)100 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  }
} Main
import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    double b = sc.nextDouble();
    long bb = (long)((double)100 * b + 0.1);
    long ans = (a * bb) / (long)100;
    System.out.println(ans);
  }
}