import java.io.*;
import java.math.*;
import java.util.*;
public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
} import java.io.*; io.* java import java.math.*; math.* java import java.util.*; util.* java public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
} Main public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	} main { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	} Scanner input = new Scanner(System.in); input new Scanner(System.in) long A = input.nextLong(); A input.nextLong() input.nextLong input String S = input.next(); S input.next() input.next input String whole = S.substring(0,1); whole S.substring(0,1) S.substring S 0 1 String decimal = S.substring(2,4); decimal S.substring(2,4) S.substring S 2 4 long B = Long.parseLong(whole); B Long.parseLong(whole) Long.parseLong Long whole long C = Long.parseLong(decimal); C Long.parseLong(decimal) Long.parseLong Long decimal long D = B*100+C; D B*100+C B*100 B 100 C long ans = A*D; ans A*D A D ans/=100 ans 100 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
} public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
} Main
import java.io.*;
import java.math.*;
import java.util.*;
public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
}