import java.util.Scanner;
import java.math.*;
public class Main{
        public static void main(String[] args){
                final Scanner cin=new Scanner(System.in);
                long a=cin.nextLong();
                double b=cin.nextDouble();
                long k=(long)Math.round(b*100);
                long mul=(a*k);
                System.out.print(mul/100);
        }   
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz