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

public class Main{
    public static void main(String args[]){
        Scanner sn = new Scanner(System.in);
        double A = sn.nextLong();
        double B = sn.nextDouble();

        BigDecimal bd1 = new BigDecimal(String.valueOf(A));
        BigDecimal bd2 = new BigDecimal(String.valueOf(B));

        BigDecimal result = bd1.multiply(bd2);
        
        System.out.println(result.setScale(0, RoundingMode.DOWN).toPlainString());
    }
}
/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