import java.util.Scanner;


class Main{
 public static void main(String args[]){
   Scanner sc = new Scanner(System.in);
   long A = sc.nextLong();
   double B = sc.nextDouble();
   long b = (long) (B*(double)100+0.5);

   System.out.println(A*b/(long)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