import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	}

} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.StringTokenizer; StringTokenizer java.util public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	}

} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st = new StringTokenizer(br.readLine()); st new StringTokenizer(br.readLine()) long a = Long.parseLong(st.nextToken()); a Long.parseLong(st.nextToken()) Long.parseLong Long st.nextToken() st.nextToken st double b = Double.parseDouble(st.nextToken()); b Double.parseDouble(st.nextToken()) Double.parseDouble Double st.nextToken() st.nextToken st long c = (long)(b * 100.0 + 0.5); c (long)(b * 100.0 + 0.5) b * 100.0 b 100.0 0.5 long res = a * c / 100; res a * c / 100 a * c a c 100 System.out.println(res) System.out.println System.out System System.out res String[] args args public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	}

} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	}

} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		long a = Long.parseLong(st.nextToken());
		double b = Double.parseDouble(st.nextToken());
		
		long c = (long)(b * 100.0 + 0.5);
		long res = a * c / 100;
		System.out.println(res);
	}

}