import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	}
}
 import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String b = sc.next(); b sc.next() sc.next sc long ans = 0; ans 0 ans += a * Long.valueOf(b.substring(0, 1)) * 100 ans a * Long.valueOf(b.substring(0, 1)) * 100 a * Long.valueOf(b.substring(0, 1)) * 100 a Long.valueOf(b.substring(0, 1)) Long.valueOf Long b.substring(0, 1) b.substring b 0 1 100 ans += a * Long.valueOf(b.substring(2, 3)) * 10 ans a * Long.valueOf(b.substring(2, 3)) * 10 a * Long.valueOf(b.substring(2, 3)) * 10 a Long.valueOf(b.substring(2, 3)) Long.valueOf Long b.substring(2, 3) b.substring b 2 3 10 ans += a * Long.valueOf(b.substring(3, 4)) ans a * Long.valueOf(b.substring(3, 4)) a Long.valueOf(b.substring(3, 4)) Long.valueOf Long b.substring(3, 4) b.substring b 3 4 ans /= 100 ans 100 System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	}
} Main
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		String b = sc.next();
		
		long ans = 0;
		ans += a * Long.valueOf(b.substring(0, 1)) * 100;
		ans += a * Long.valueOf(b.substring(2, 3)) * 10;
		ans += a * Long.valueOf(b.substring(3, 4));
		ans /= 100;
		
		System.out.println(ans);
		
		sc.close();
	}
}

