import java.math.BigDecimal;
import java.util.Scanner;
public class Main {

    public static void main(String[] args) {
      Scanner sc=new Scanner(System.in);
      String inp=sc.nextLine();
      String[] ip = inp.split(" ");
      String a = ip[0];
      String b = ip[1];
      BigDecimal c = new BigDecimal(a);
      BigDecimal d = new BigDecimal(b);
      BigDecimal res = c.multiply(d);
      long ans = res.setScale(0, BigDecimal.ROUND_FLOOR).longValue();
      System.out.println(ans);
    }
}
/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