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

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    }
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    } main {
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc BigDecimal ba = BigDecimal.valueOf(a); ba BigDecimal.valueOf(a) BigDecimal.valueOf BigDecimal a String b = sc.next(); b sc.next() sc.next sc BigDecimal bb = new BigDecimal(b); bb new BigDecimal(b) System.out.println(ba.multiply(bb).longValue()) System.out.println System.out System System.out ba.multiply(bb).longValue() ba.multiply(bb).longValue ba.multiply(bb) ba.multiply ba bb String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    }
} Main
import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        // 整数の入力
        long a = sc.nextLong();
        BigDecimal ba = BigDecimal.valueOf(a);
        String b = sc.next();
        BigDecimal bb = new BigDecimal(b);


        System.out.println(ba.multiply(bb).longValue());
    }
}