import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Scanner;

public class Main {
    private static final int MOD = 1_000_000_007;
    private static final String YES = "Yes";
    private static final String NO = "No";

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    }

    private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    }
} import java.math.BigDecimal; BigDecimal java.math import java.math.RoundingMode; RoundingMode java.math import java.util.Scanner; Scanner java.util public class Main {
    private static final int MOD = 1_000_000_007;
    private static final String YES = "Yes";
    private static final String NO = "No";

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    }

    private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    }
} Main private static final int MOD = 1_000_000_007; MOD 1_000_000_007 private static final String YES = "Yes"; YES "Yes" private static final String NO = "No"; NO "No" public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    } main {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc double B = sc.nextDouble(); B sc.nextDouble() sc.nextDouble sc System.out.println(solve(A, B)) System.out.println System.out System System.out solve(A, B) solve A B String[] args args private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    } solve {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    } BigDecimal b = BigDecimal.valueOf(A); b BigDecimal.valueOf(A) BigDecimal.valueOf BigDecimal A b = b.multiply(BigDecimal.valueOf(B)) b b.multiply(BigDecimal.valueOf(B)) b.multiply b BigDecimal.valueOf(B) BigDecimal.valueOf BigDecimal B return b.setScale(0, RoundingMode.DOWN).toString(); b.setScale(0, RoundingMode.DOWN).toString() b.setScale(0, RoundingMode.DOWN).toString b.setScale(0, RoundingMode.DOWN) b.setScale b 0 RoundingMode.DOWN RoundingMode RoundingMode.DOWN long A A double B B public class Main {
    private static final int MOD = 1_000_000_007;
    private static final String YES = "Yes";
    private static final String NO = "No";

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    }

    private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    }
} public class Main {
    private static final int MOD = 1_000_000_007;
    private static final String YES = "Yes";
    private static final String NO = "No";

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    }

    private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    }
} Main
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Scanner;

public class Main {
    private static final int MOD = 1_000_000_007;
    private static final String YES = "Yes";
    private static final String NO = "No";

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        long A = sc.nextLong();
        double B = sc.nextDouble();

        System.out.println(solve(A, B));
    }

    private static String solve(long A, double B) {
        BigDecimal b = BigDecimal.valueOf(A);
        b = b.multiply(BigDecimal.valueOf(B));


        return b.setScale(0, RoundingMode.DOWN).toString();
    }
}