import java.io.*;
import java.math.*;
import java.util.*;
public class Main { 

	public static void main(String[] args) { //
		Scanner input = new Scanner(System.in);
		long A = input.nextLong();
		String S = input.next();
		String whole = S.substring(0,1);
		String decimal = S.substring(2,4);
		long B = Long.parseLong(whole);
		long C = Long.parseLong(decimal);
		long D = B*100+C;
		long ans = A*D;
		ans/=100;
		System.out.println(ans);
	}	
}
/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