
import java.util.*;

class Main {


	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		double B = sc.nextDouble();
		
		long ans = 0;
		ans = A * (Math.round(B * 100)) / 100 ;
		
		System.out.println(ans);

		
	}

}

 import java.util.*; util.* java class Main {


	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		double B = sc.nextDouble();
		
		long ans = 0;
		ans = A * (Math.round(B * 100)) / 100 ;
		
		System.out.println(ans);

		
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		double B = sc.nextDouble();
		
		long ans = 0;
		ans = A * (Math.round(B * 100)) / 100 ;
		
		System.out.println(ans);

		
	} main {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		double B = sc.nextDouble();
		
		long ans = 0;
		ans = A * (Math.round(B * 100)) / 100 ;
		
		System.out.println(ans);

		
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc double B = sc.nextDouble(); B sc.nextDouble() sc.nextDouble sc long ans = 0; ans 0 ans = A * (Math.round(B * 100)) / 100 ans A * (Math.round(B * 100)) / 100 A * (Math.round(B * 100)) A (Math.round(B * 100)) Math.round Math B * 100 B 100 100 System.out.println(ans) System.out.println System.out System System.out ans String[] args args

import java.util.*;

class Main {


	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A = sc.nextLong();
		double B = sc.nextDouble();
		
		long ans = 0;
		ans = A * (Math.round(B * 100)) / 100 ;
		
		System.out.println(ans);

		
	}

}


