import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {

			String a = sc.next();
			String b = sc.next();
			
			BigDecimal bigA = new BigDecimal(a);
			BigDecimal bigB = new BigDecimal(b);
			
			
			BigDecimal c = bigA.multiply(bigB);
			
			long ans = c.longValue();
			
			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