import java.util.*;
import java.io.*;
import java.lang.Math;
public class Main {
    public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    }
} import java.util.*; util.* java import java.io.*; io.* java import java.lang.Math; Math java.lang public class Main {
    public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    }
} Main public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    } main {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    } BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) StringTokenizer s = new StringTokenizer(in.readLine()); s new StringTokenizer(in.readLine()) long a = Long.parseLong(s.nextToken()); a Long.parseLong(s.nextToken()) Long.parseLong Long s.nextToken() s.nextToken s String bS = s.nextToken(); bS s.nextToken() s.nextToken s int bTop = Integer.parseInt(bS.substring(0,1)); bTop Integer.parseInt(bS.substring(0,1)) Integer.parseInt Integer bS.substring(0,1) bS.substring bS 0 1 int bBottom = Integer.parseInt(bS.substring(2)); bBottom Integer.parseInt(bS.substring(2)) Integer.parseInt Integer bS.substring(2) bS.substring bS 2 int c = bTop * 100 + bBottom; c bTop * 100 + bBottom bTop * 100 bTop 100 bBottom long result = a * c / 100; result a * c / 100 a * c a c 100 System.out.println(result) System.out.println System.out System System.out result String [] args args public class Main {
    public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    }
} public class Main {
    public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    }
} Main
import java.util.*;
import java.io.*;
import java.lang.Math;
public class Main {
    public static void main (String [] args) throws IOException
    {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        
        StringTokenizer s = new StringTokenizer(in.readLine());
        
        long a = Long.parseLong(s.nextToken());
        String bS = s.nextToken();
        int bTop = Integer.parseInt(bS.substring(0,1));
        int bBottom = Integer.parseInt(bS.substring(2));
        int c = bTop * 100 + bBottom;
        long result = a * c / 100;

        System.out.println(result);
    }
}