
	import java.util.Scanner;

	public class Main {

		static long mod = 1000000007;

		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		}
	} import java.util.Scanner; Scanner java.util public class Main {

		static long mod = 1000000007;

		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		}
	} Main static long mod = 1000000007; mod 1000000007 public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		} main {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String[] t = sc.nextLine().split(" "); t sc.nextLine().split(" ") sc.nextLine().split sc.nextLine() sc.nextLine sc " " long n = Long.parseLong(t[0]); n Long.parseLong(t[0]) Long.parseLong Long t[0] t 0 long k = Long.parseLong(t[1].replaceAll("\\.", "")); k Long.parseLong(t[1].replaceAll("\\.", "")) Long.parseLong Long t[1].replaceAll("\\.", "") t[1].replaceAll t[1] t 1 "\\." "" System.out.println(n * k / 100) System.out.println System.out System System.out n * k / 100 n * k n k 100 String[] args args public class Main {

		static long mod = 1000000007;

		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		}
	} public class Main {

		static long mod = 1000000007;

		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		}
	} Main

	import java.util.Scanner;

	public class Main {

		static long mod = 1000000007;

		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			String[] t = sc.nextLine().split(" ");
			long n = Long.parseLong(t[0]);
			long k = Long.parseLong(t[1].replaceAll("\\.", ""));

			System.out.println(n * k / 100);
		}
	}
