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 bd = new BigDecimal(a);
        BigDecimal bdb = new BigDecimal(b);
         BigDecimal ans = bd.multiply(bdb);
         BigDecimal anss = ans.setScale(0,BigDecimal.ROUND_DOWN);
        System.out.println(anss);
    }
}

/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