import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    } main {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String[] s = sc.next().split("[.]"); s sc.next().split("[.]") sc.next().split sc.next() sc.next sc "[.]" long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]); b Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]) Integer.valueOf(s[0]) * 100 Integer.valueOf(s[0]) Integer.valueOf Integer s[0] s 0 100 Integer.valueOf(s[1]) Integer.valueOf Integer s[1] s 1 long result = (a * b) / 100; result (a * b) / 100 (a * b) a b 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){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    }
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String[] s = sc.next().split("[.]");

        long b = Integer.valueOf(s[0]) * 100 + Integer.valueOf(s[1]);

        long result = (a * b) / 100;

        System.out.println(result);
    }
}
