import java.util.*;

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

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	}
} Main public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	} main {

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	} Scanner keyboard = new Scanner(System.in); keyboard new Scanner(System.in) long A = keyboard.nextLong(); A keyboard.nextLong() keyboard.nextLong keyboard String B = keyboard.next(); B keyboard.next() keyboard.next keyboard long NB = 0; NB 0 String nb = ""; nb "" for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		} int b = 0; int b = 0; b 0 b<4 b 4 b++ b++ b {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		} {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		} if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			} B.charAt(b)!= '.' B.charAt(b) B.charAt B b '.' {
				nb += B.charAt(b);
			} nb += B.charAt(b) nb B.charAt(b) B.charAt B b NB = Integer.parseInt(nb) NB Integer.parseInt(nb) Integer.parseInt Integer nb System.out.println(NB*A/100) System.out.println System.out System System.out NB*A/100 NB*A NB A 100 keyboard.close() keyboard.close keyboard String[] args args public class Main {
	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	}
} public class Main {
	public static void main(String[] args) {

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	}
} Main
import java.util.*;

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

		Scanner keyboard = new Scanner(System.in);

		long A = keyboard.nextLong();
		String B = keyboard.next();
		
		long NB = 0;
		String nb = "";
		
		for(int b = 0;b<4; b++) {
			if( B.charAt(b)!= '.') {
				nb += B.charAt(b);
			}
		}
		NB = Integer.parseInt(nb);
		
		System.out.println(NB*A/100);
		keyboard.close();
	}
}