using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;
using System.Numerics;

namespace abc169
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
            if (File.Exists("input.txt"))
            {
                Console.SetIn(new StreamReader("input.txt"));
            }
            solve_abc169C();
            Console.Out.Flush();
        }

        public static void solve_abc169C()
        {
            string[] str = Console.ReadLine().Split(" ");
            
            
            long a = Convert.ToInt64(str[0]);
            double b = Convert.ToDouble(str[1]);
            long x = Convert.ToInt64(b * 100);
            Console.WriteLine((a * x) / 100);
        }

        public static void solve_abc169B()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            long[] a = Array.ConvertAll(Console.ReadLine().Split(), long.Parse);
            long mult = 1;
            long limit = 1000000000000000000;
            bool ok = true;
            bool hasZero = false;
            for (int i = 0; i < n; i++)
            {
                if (a[i] > 0)
                {
                    mult *= a[i];
                    if (mult > limit || mult <= 0)
                    {
                        ok = false;
                    }
                }
                else
                {
                    hasZero = true;
                    break;
                }
            }
            if (hasZero)
            {
                Console.WriteLine(0);
            }
            else if (!ok)
            {
                Console.WriteLine(-1);
            }
            else
            {
                Console.WriteLine(mult);
            }
        }

        public static void solve_abc169A()
        {
            int[] ab = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
            Console.WriteLine(ab[0] * ab[1]);
        }

        /*
            int[] test = new int[7]  {3, 5, 7, 9, 10, 11, 13};
            int[] keys = new int[9] {1, 3, 4, 5, 8, 11, 12, 13, 14};
            for (int i = 0; i < keys.Length; i++)
            {
                Console.WriteLine(binSearch(test, keys[i]));
            }
        */
        public static int binSearch(int[] a, int x)
        {
            int l = 0;
            int r = a.Length - 1;
            while (l <= r)
            {
                int mid = (l + r) / 2;
                if (a[mid] == x)
                {
                    return mid;
                }
                else if (a[mid] > x)
                {
                    r = mid - 1;
                }
                else
                {
                    l = mid + 1;
                }
            }
            return -1;
        }

        public static int binSearchLeft(int[] a, int x)
        {
            int l = 0;
            int r = a.Length - 1;
            while (l < r)
            {
                int mid = (l + r) / 2;
                if (a[mid] < x)
                {
                    l = mid + 1;
                }
                else
                {
                    r = mid;
                }
            }
            return l;
        }
    }
}

Measured memory_bytes: 28516