import java.util.*;
import java.math.BigDecimal;

public class Main {
  public static void main (String args[]) {
    Scanner sc = new Scanner(System.in);
    
    String A = sc.next();
    String B = sc.next();
    BigDecimal b1 = new BigDecimal(A);
    BigDecimal b2 = new BigDecimal(B);
    BigDecimal b3 = b1.multiply(b2);
    BigDecimal bd1 = b3.setScale(0, BigDecimal.ROUND_DOWN);
    System.out.println(bd1);
  }
}
/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