import java.math.BigDecimal;
import java.util.*;

public class Main {

    static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L);
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    }

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

    static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L);
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    }

} Main static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L); MAX new BigDecimal(1_000_000_000_000_000_000L) public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    } main {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc long b = Long.valueOf(sc.next().replace(".", "")); b Long.valueOf(sc.next().replace(".", "")) Long.valueOf Long sc.next().replace(".", "") sc.next().replace sc.next() sc.next sc "." "" long ans = a * b / 100; ans a * b / 100 a * b a b 100 System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc String[] args args public class Main {

    static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L);
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    }

} public class Main {

    static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L);
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    }

} Main
import java.math.BigDecimal;
import java.util.*;

public class Main {

    static BigDecimal MAX = new BigDecimal(1_000_000_000_000_000_000L);
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        long b = Long.valueOf(sc.next().replace(".", ""));
        long ans = a * b / 100;
        System.out.println(ans);
        sc.close();

    }

}
