import java.util.*;

class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
      long A =sc.nextLong(),ans=0;
      String B = sc.next();
      ans += 100*A*Character.getNumericValue(B.charAt(0));
      ans += 10*A*Character.getNumericValue(B.charAt(2));
      ans += A*Character.getNumericValue(B.charAt(3));
      System.out.println(ans/100);
	}
} import java.util.*; util.* java class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
      long A =sc.nextLong(),ans=0;
      String B = sc.next();
      ans += 100*A*Character.getNumericValue(B.charAt(0));
      ans += 10*A*Character.getNumericValue(B.charAt(2));
      ans += A*Character.getNumericValue(B.charAt(3));
      System.out.println(ans/100);
	}
} Main static Scanner sc = new Scanner(System.in); sc new Scanner(System.in) public static void main(String[] args) {
      long A =sc.nextLong(),ans=0;
      String B = sc.next();
      ans += 100*A*Character.getNumericValue(B.charAt(0));
      ans += 10*A*Character.getNumericValue(B.charAt(2));
      ans += A*Character.getNumericValue(B.charAt(3));
      System.out.println(ans/100);
	} main {
      long A =sc.nextLong(),ans=0;
      String B = sc.next();
      ans += 100*A*Character.getNumericValue(B.charAt(0));
      ans += 10*A*Character.getNumericValue(B.charAt(2));
      ans += A*Character.getNumericValue(B.charAt(3));
      System.out.println(ans/100);
	} long A =sc.nextLong() A sc.nextLong() sc.nextLong sc ans=0; ans 0 String B = sc.next(); B sc.next() sc.next sc ans += 100*A*Character.getNumericValue(B.charAt(0)) ans 100*A*Character.getNumericValue(B.charAt(0)) 100*A*Character.getNumericValue(B.charAt(0)) 100 A Character.getNumericValue(B.charAt(0)) Character.getNumericValue Character B.charAt(0) B.charAt B 0 ans += 10*A*Character.getNumericValue(B.charAt(2)) ans 10*A*Character.getNumericValue(B.charAt(2)) 10*A*Character.getNumericValue(B.charAt(2)) 10 A Character.getNumericValue(B.charAt(2)) Character.getNumericValue Character B.charAt(2) B.charAt B 2 ans += A*Character.getNumericValue(B.charAt(3)) ans A*Character.getNumericValue(B.charAt(3)) A Character.getNumericValue(B.charAt(3)) Character.getNumericValue Character B.charAt(3) B.charAt B 3 System.out.println(ans/100) System.out.println System.out System System.out ans/100 ans 100 String[] args args
import java.util.*;

class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
      long A =sc.nextLong(),ans=0;
      String B = sc.next();
      ans += 100*A*Character.getNumericValue(B.charAt(0));
      ans += 10*A*Character.getNumericValue(B.charAt(2));
      ans += A*Character.getNumericValue(B.charAt(3));
      System.out.println(ans/100);
	}
}