import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) throws Exception {
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {

            String[] in = br.readLine().split(" ");

            br.close();

            BigDecimal x = new BigDecimal(in[0]);
            BigDecimal y = new BigDecimal(in[1]);

            System.out.println(x.multiply(y).toBigInteger());

        }
    }
}
/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