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

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    }
} import java.math.BigDecimal; BigDecimal java.math import java.math.BigInteger; BigInteger java.math import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc BigDecimal bd = new BigDecimal(sc.next()); bd new BigDecimal(sc.next()) bd = bd.multiply(new BigDecimal("100.0")) bd bd.multiply(new BigDecimal("100.0")) bd.multiply bd new BigDecimal("100.0") BigInteger bi = bd.toBigInteger(); bi bd.toBigInteger() bd.toBigInteger bd long b = Long.parseLong(bi.toString()); b Long.parseLong(bi.toString()) Long.parseLong Long bi.toString() bi.toString bi 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 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    }
} Main
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        BigDecimal bd = new BigDecimal(sc.next());
        bd = bd.multiply(new BigDecimal("100.0"));
        BigInteger bi = bd.toBigInteger();
        long b = Long.parseLong(bi.toString());
        long ans = (a*b)/100;
        System.out.println(ans);
    }
}
