import java.util.Scanner;

public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
} Main static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	} toLong {
			long num=(long)(N*100+0.001);
			return num;
	} long num=(long)(N*100+0.001); num (long)(N*100+0.001) N*100 N 100 0.001 return num; num double N N public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	} 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 result=Math.floorDiv(A*toLong(B),100l); result Math.floorDiv(A*toLong(B),100l) Math.floorDiv Math A*toLong(B) A toLong(B) toLong B 100l System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
} public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
} Main
import java.util.Scanner;

public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
}
