import java.util.Scanner;

public class Main {
	static long toLong(double N) {
			long num=(long)(N*100+0.001);
			return num;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long A=sc.nextLong();
		double B=sc.nextDouble();
		sc.close();
		long result=Math.floorDiv(A*toLong(B),100l);
		System.out.println(result);
	}
}

/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