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

public class Main {

    Scanner sc = new Scanner(System.in);

    int MOD = 998244353;

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    }
} import java.math.BigDecimal; BigDecimal java.math import java.util.*; util.* java public class Main {

    Scanner sc = new Scanner(System.in);

    int MOD = 998244353;

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    }
} Main Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int MOD = 998244353; MOD 998244353 public static void main(String[] args) {
        new Main().run();
    } main {
        new Main().run();
    } new Main().run() new Main().run new Main() String[] args args void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    } run {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    } long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc double b = sc.nextDouble(); b sc.nextDouble() sc.nextDouble sc long lb = Math.round(b*100); lb Math.round(b*100) Math.round Math b*100 b 100 System.out.println(a*lb/100) System.out.println System.out System System.out a*lb/100 a*lb a lb 100 public class Main {

    Scanner sc = new Scanner(System.in);

    int MOD = 998244353;

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    }
} public class Main {

    Scanner sc = new Scanner(System.in);

    int MOD = 998244353;

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    }
} Main
import java.math.BigDecimal;
import java.util.*;

public class Main {

    Scanner sc = new Scanner(System.in);

    int MOD = 998244353;

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        long a = sc.nextLong();
        double b = sc.nextDouble();
        long lb = Math.round(b*100);

        System.out.println(a*lb/100);
    }
}
