import java.math.BigDecimal;
import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
} import java.math.BigDecimal; BigDecimal java.math import java.util.*; util.* java public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	} main {
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) BigDecimal a = new BigDecimal(scan.next()); a new BigDecimal(scan.next()) BigDecimal b = new BigDecimal(scan.next()); b new BigDecimal(scan.next()) BigDecimal tmp = a.multiply(b); tmp a.multiply(b) a.multiply a b long ans = tmp.longValue(); ans tmp.longValue() tmp.longValue tmp System.out.print(ans) System.out.print System.out System System.out ans String[] args args public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
} public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
} Main
import java.math.BigDecimal;
import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal a = new BigDecimal(scan.next());
		BigDecimal b = new BigDecimal(scan.next());
		BigDecimal tmp = a.multiply(b);
		long ans = tmp.longValue();
		System.out.print(ans);


	}
}