
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	}

} Main public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	} main {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	} Scanner s = new Scanner(System.in); s new Scanner(System.in) long a = s.nextLong(); a s.nextLong() s.nextLong s String b_s = s.next(); b_s s.next() s.next s long b = 0; b 0 int base = 1; base 1 for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		} int i = b_s.length()-1; int i = b_s.length()-1; i b_s.length()-1 b_s.length() b_s.length b_s 1 i >= 0 i 0 i-- i-- i {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		} {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		} char c = b_s.charAt(i); c b_s.charAt(i) b_s.charAt b_s i if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    } c != '.' c '.' {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    } b += Character.getNumericValue(b_s.charAt(i)) * base b Character.getNumericValue(b_s.charAt(i)) * base Character.getNumericValue(b_s.charAt(i)) Character.getNumericValue Character b_s.charAt(i) b_s.charAt b_s i base base *= 10 base 10 long mul = (long)(a * b); mul (long)(a * b) a b System.out.println(mul/100) System.out.println System.out System System.out mul/100 mul 100 String[] args args public class Main {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	}

} public class Main {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	}

} Main

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);

		long a = s.nextLong();
		
		String b_s = s.next();
		
		long b = 0;
		int base = 1;
		for ( int i = b_s.length()-1; i >= 0; i-- ) {
		    char c = b_s.charAt(i);
		    if (c != '.') {
		        b += Character.getNumericValue(b_s.charAt(i)) * base;
		        base *= 10;
		    }
		}
		
		long mul = (long)(a * b);
		

		System.out.println(mul/100);

		

	}

}
