import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    }

}
 import java.util.*; util.* java public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    } main {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc long B = (long)(sc.nextDouble()*100+0.9); B (long)(sc.nextDouble()*100+0.9) sc.nextDouble()*100 sc.nextDouble() sc.nextDouble sc 100 0.9 long res = A*B/100; res A*B/100 A*B A B 100 System.out.println(res) System.out.println System.out System System.out res String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    }

} Main
import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = (long)(sc.nextDouble()*100+0.9);
        
        long res = A*B/100;
        
        System.out.println(res);
    }

}

