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