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

public class Main{
    public static void main(String[] args){
        Scanner scan = new java.util.Scanner(System.in);
        BigDecimal a = new BigDecimal(Long.toString(scan.nextLong()));
        BigDecimal b = new BigDecimal(Double.toString(scan.nextDouble()));
        System.out.println(a.multiply(b).setScale(0, BigDecimal.ROUND_DOWN));
        scan.close();
    }
}
/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