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();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	}
} 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();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long a = sc.nextLong();
		String b = sc.next();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	} main {
		Scanner sc = new Scanner(System.in);
		
		long a = sc.nextLong();
		String b = sc.next();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	} 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 String d = ""; d "" for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		} int i = 0; int i = 0; i 0 i< b.length() i b.length() b.length b i++ i++ i {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		} {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		} if(b.charAt(i) == '.') {
				continue;
			} b.charAt(i) == '.' b.charAt(i) b.charAt b i '.' {
				continue;
			} continue; d+=b.charAt(i) d b.charAt(i) b.charAt b i int c= new Integer(d).intValue(); c new Integer(d).intValue() new Integer(d).intValue new Integer(d) System.out.println(a*c/100) System.out.println System.out System System.out a*c/100 a*c a c 100 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();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long a = sc.nextLong();
		String b = sc.next();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	}
} 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();
		String d = "";
		
		for(int i = 0; i< b.length(); i++) {
			if(b.charAt(i) == '.') {
				continue;
			}
			d+=b.charAt(i);
		}
		int c= new Integer(d).intValue();
		System.out.println(a*c/100);
	}
}