import java.io.BufferedReader; 
import java.io.InputStreamReader; 
import java.io.IOException; 
import java.util.StringTokenizer; 
import java.util.Arrays;
public class Main {
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    }
    public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    }

} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io import java.util.StringTokenizer; StringTokenizer java.util import java.util.Arrays; Arrays java.util public class Main {
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    }
    public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    }

} Main public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    } main {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    } FastReader fs= new FastReader(); fs new FastReader() long A= fs.nextLong(); A fs.nextLong() fs.nextLong fs String B=fs.next(); B fs.next() fs.next fs long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100; res (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100 (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0'))) A (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')) ((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0') ((B.charAt(0)-'0')*100) (B.charAt(0)-'0') B.charAt(0) B.charAt B 0 '0' 100 ((B.charAt(2)-'0')*10) (B.charAt(2)-'0') B.charAt(2) B.charAt B 2 '0' 10 (B.charAt(3)-'0') B.charAt(3) B.charAt B 3 '0' 100 System.out.println(res) System.out.println System.out System System.out res String args[] args static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    } FastReader BufferedReader br; br StringTokenizer st; st public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       } FastReader {
           br=new BufferedReader(new InputStreamReader(System.in));
       } br=new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       } next {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       } while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           } st==null ||!st.hasMoreElements() st==null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           } try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               } catch(IOException e)
               {
                   e.printStackTrace();
               } IOException e {
                   e.printStackTrace();
               } e.printStackTrace() e.printStackTrace e {
                   st= new StringTokenizer(br.readLine());
               } st= new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt()
       {
           return Integer.parseInt(next());
       } nextInt {
           return Integer.parseInt(next());
       } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong()
       {
           return Long.parseLong(next());
       } nextLong {
           return Long.parseLong(next());
       } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public class Main {
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    }
    public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    }

} public class Main {
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    }
    public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    }

} Main
import java.io.BufferedReader; 
import java.io.InputStreamReader; 
import java.io.IOException; 
import java.util.StringTokenizer; 
import java.util.Arrays;
public class Main {
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
       public  FastReader()
       {
           br=new BufferedReader(new InputStreamReader(System.in));
       }
       String next()
       {
           while(st==null ||!st.hasMoreElements())
           {
               try
               {
                   st= new StringTokenizer(br.readLine());
               }
               catch(IOException e)
               {
                   e.printStackTrace();
               }
           }
           return st.nextToken();
       }
      
       int nextInt()
       {
           return Integer.parseInt(next());
       }
       long nextLong()
       {
           return Long.parseLong(next());
       }
    }
    public static void main(String args[]) throws IOException
    {
        FastReader fs= new FastReader();
        long A= fs.nextLong();
        String B=fs.next();
        long res= (A* (((B.charAt(0)-'0')*100) +((B.charAt(2)-'0')*10) + (B.charAt(3)-'0')))/100;
        System.out.println(res);
    }

}