import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    int b = Integer.parseInt(clean(sc.nextLine()));
    sc.close();
    long r = (a * b) / 100;
    System.out.println(r);
  }
  
  private static String clean(String n) {
    int s = n.length();
    String ns = "";
    for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    }
    return ns;
  }
} import java.util.Scanner; Scanner java.util class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    int b = Integer.parseInt(clean(sc.nextLine()));
    sc.close();
    long r = (a * b) / 100;
    System.out.println(r);
  }
  
  private static String clean(String n) {
    int s = n.length();
    String ns = "";
    for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    }
    return ns;
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    int b = Integer.parseInt(clean(sc.nextLine()));
    sc.close();
    long r = (a * b) / 100;
    System.out.println(r);
  } main {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    int b = Integer.parseInt(clean(sc.nextLine()));
    sc.close();
    long r = (a * b) / 100;
    System.out.println(r);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc int b = Integer.parseInt(clean(sc.nextLine())); b Integer.parseInt(clean(sc.nextLine())) Integer.parseInt Integer clean(sc.nextLine()) clean sc.nextLine() sc.nextLine sc sc.close() sc.close sc long r = (a * b) / 100; r (a * b) / 100 (a * b) a b 100 System.out.println(r) System.out.println System.out System System.out r String[] args args private static String clean(String n) {
    int s = n.length();
    String ns = "";
    for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    }
    return ns;
  } clean {
    int s = n.length();
    String ns = "";
    for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    }
    return ns;
  } int s = n.length(); s n.length() n.length n String ns = ""; ns "" for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    } int i = 0; int i = 0; i 0 i < s i s i++ i++ i {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    } {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    } char c = n.charAt(i); c n.charAt(i) n.charAt n i if(c != ' ' && c != '.') ns += c; c != ' ' && c != '.' c != ' ' c ' ' c != '.' c '.' ns += c ns c return ns; ns String n n
import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long a = sc.nextLong();
    int b = Integer.parseInt(clean(sc.nextLine()));
    sc.close();
    long r = (a * b) / 100;
    System.out.println(r);
  }
  
  private static String clean(String n) {
    int s = n.length();
    String ns = "";
    for(int i = 0; i < s; i++) {
      char c = n.charAt(i);
      if(c != ' ' && c != '.') ns += c;
    }
    return ns;
  }
}