import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
 
 
public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 }
} import java.util.*; util.* java import java.math.RoundingMode; RoundingMode java.math import java.math.BigDecimal; BigDecimal java.math public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 }
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 } main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 } 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 BigDecimal a1 = new BigDecimal(a); a1 new BigDecimal(a) BigDecimal ans = a1.multiply(BigDecimal.valueOf(b)); ans a1.multiply(BigDecimal.valueOf(b)) a1.multiply a1 BigDecimal.valueOf(b) BigDecimal.valueOf BigDecimal b System.out.println(ans.longValue()) System.out.println System.out System System.out ans.longValue() ans.longValue ans String[] args args public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 }
} public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 }
} Main
import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
 
 
public class Main{
	 public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		BigDecimal a1 = new BigDecimal(a);
		BigDecimal ans = a1.multiply(BigDecimal.valueOf(b));
		System.out.println(ans.longValue());
	 }
}