import java.util.*;
import java.io.*;
import static java.lang.Math.*;

public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	}

} import java.util.*; util.* java import java.io.*; io.* java import static java.lang.Math.*; import static java.lang.Math.*; import static java.lang.Math.*; public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	}

} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	} 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 result = 0; result 0 b += 0.001 b 0.001 long B = Double.valueOf(b*100).longValue(); B Double.valueOf(b*100).longValue() Double.valueOf(b*100).longValue Double.valueOf(b*100) Double.valueOf Double b*100 b 100 result = (a*B)/100 result (a*B)/100 (a*B) a B 100 System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	}

} public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	}

} Main
import java.util.*;
import java.io.*;
import static java.lang.Math.*;

public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		long a = sc.nextLong();
		double b = sc.nextDouble();
		
		// 計算
		long result = 0;
		b += 0.001;
		long B = Double.valueOf(b*100).longValue();
		result = (a*B)/100;
		
		// 出力
		System.out.println(result);
	}

}
