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

public class Main {

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

		long A = sc.nextLong();
		BigDecimal B = sc.nextBigDecimal();
		int C = 100;
//		BigDecimal変換
		BigDecimal bA = new BigDecimal(A);
		BigDecimal bC = new BigDecimal(C);

		B = B.multiply(bC); //少数を整数に直す
		BigDecimal pop = bA.multiply(B);
		pop = pop.divide(bC);
		pop = pop.setScale(0, BigDecimal.ROUND_DOWN);

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