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

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	}
} 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);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	}
} Main public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	} 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 sc.close() sc.close sc long d = (long)(b *1000); d (long)(b *1000) b 1000 long c = a*d; c a*d a d c = c /100 c c /100 c 100 System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000"))) System.out.println System.out System System.out new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")) new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue new BigDecimal(a).multiply(new BigDecimal(d)) new BigDecimal(a).multiply new BigDecimal(a) new BigDecimal(d) new BigDecimal("1000") 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();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	}
} public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	}
} Main
import java.math.BigDecimal;
import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		double b = sc.nextDouble();
		sc.close();
		long d = (long)(b *1000);
		long c = a*d;
		;
		c = c /100;
		System.out.println(new BigDecimal(a).multiply(new BigDecimal(d)).divideToIntegralValue(new BigDecimal("1000")));
	}
}