import java.util.*;
import java.io.*;
public class Main {
 
	public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	}
 
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
 
	public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	}
 
} Main public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	} main {
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	} int num = 998244353; num 998244353 BufferedReader bf = new BufferedReader(new InputStreamReader(System.in)); bf new BufferedReader(new InputStreamReader(System.in)) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) StringTokenizer st = new StringTokenizer(bf.readLine()); st new StringTokenizer(bf.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 int c = (int)(b*100.0001); c (int)(b*100.0001) b 100.0001 long d = a*(long)(c); d a*(long)(c) a (long)(c) out.println((d-((a%100)*(c%100))%100)/((long)(100))) out.println out (d-((a%100)*(c%100))%100)/((long)(100)) (d-((a%100)*(c%100))%100) d ((a%100)*(c%100))%100 ((a%100)*(c%100)) (a%100) a 100 (c%100) c 100 100 ((long)(100)) out.close() out.close out String[] args args public class Main {
 
	public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	}
 
} public class Main {
 
	public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	}
 
} Main
import java.util.*;
import java.io.*;
public class Main {
 
	public static void main(String[] args) throws Exception{
		int num = 998244353;
 
		// TODO Auto-generated method stub
 		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
 		PrintWriter out = new PrintWriter(System.out);
 		StringTokenizer st = new StringTokenizer(bf.readLine());
 		long a = Long.parseLong(st.nextToken());
 		double b = Double.parseDouble(st.nextToken());
 		int c = (int)(b*100.0001);
 		long d = a*(long)(c);
 		out.println((d-((a%100)*(c%100))%100)/((long)(100)));
 		out.close();
 		
 	}
 
}