import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	}
} Main public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	} main {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) long n =sc.nextLong(); n sc.nextLong() sc.nextLong sc int f = (int)Math.floor((double)100*sc.nextDouble()); f (int)Math.floor((double)100*sc.nextDouble()) Math.floor Math (double)100*sc.nextDouble() (double)100 sc.nextDouble() sc.nextDouble sc long temp = n*f; temp n*f n f temp/=(long)100 temp (long)100 System.out.println(temp) System.out.println System.out System System.out temp String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	}
} Main
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n =sc.nextLong();
		int f = (int)Math.floor((double)100*sc.nextDouble());
		long temp = n*f;
		temp/=(long)100;
		System.out.println(temp);
	}
}
