
import java.math.BigInteger;
import java.util.*;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	}

} import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	}

} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	} main {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = Long.parseLong(sc.next()); a Long.parseLong(sc.next()) Long.parseLong Long sc.next() sc.next sc long b = Long.parseLong(sc.next().replace(".", "")); b Long.parseLong(sc.next().replace(".", "")) Long.parseLong Long sc.next().replace(".", "") sc.next().replace sc.next() sc.next sc "." "" BigInteger bigA = BigInteger.valueOf(a); bigA BigInteger.valueOf(a) BigInteger.valueOf BigInteger a BigInteger bigC = bigA.multiply(BigInteger.valueOf(b)); bigC bigA.multiply(BigInteger.valueOf(b)) bigA.multiply bigA BigInteger.valueOf(b) BigInteger.valueOf BigInteger b BigInteger bigD = bigC.divide(BigInteger.valueOf(100)); bigD bigC.divide(BigInteger.valueOf(100)) bigC.divide bigC BigInteger.valueOf(100) BigInteger.valueOf BigInteger 100 System.out.println(bigD.longValue()) System.out.println System.out System System.out bigD.longValue() bigD.longValue bigD String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	}

} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	}

} Main

import java.math.BigInteger;
import java.util.*;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next().replace(".", ""));

		BigInteger bigA = BigInteger.valueOf(a);
		BigInteger bigC = bigA.multiply(BigInteger.valueOf(b));
		BigInteger bigD = bigC.divide(BigInteger.valueOf(100));
		
		System.out.println(bigD.longValue());

	}

}