import java.math.BigDecimal;
import java.util.Scanner;
class Main{
    public static void main(String args[]){
        Scanner scan = new Scanner(System.in);
        double a = scan.nextDouble();
        double b = scan.nextDouble();
        BigDecimal aa = BigDecimal.valueOf(a);
        BigDecimal bb = BigDecimal.valueOf(b);
        BigDecimal cc = aa.multiply(bb);
        BigDecimal sum = cc.setScale(0, BigDecimal.ROUND_DOWN);

        System.out.println(sum);
    }
}
/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