import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc int b =(int)(sc.nextDouble()*100+0.01); b (int)(sc.nextDouble()*100+0.01) sc.nextDouble()*100 sc.nextDouble() sc.nextDouble sc 100 0.01 System.out.println((a*b)/100) System.out.println System.out System System.out (a*b)/100 (a*b) a b 100 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();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		int b =(int)(sc.nextDouble()*100+0.01);
				
		System.out.println((a*b)/100);
		
		
		sc.close();
	}
}
