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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));

        StringTokenizer st = new StringTokenizer(br.readLine());
        BigDecimal a = new BigDecimal(st.nextToken());
        BigDecimal b = new BigDecimal(st.nextToken());

        BigDecimal prod = a.multiply(b);
        prod = prod.setScale(0, BigDecimal.ROUND_DOWN);

        pw.println(prod);
        pw.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