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);
	}
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util 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);
	}
} 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);
	} main {
		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);
	} Scanner sc =  new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc BigDecimal B = sc.nextBigDecimal(); B sc.nextBigDecimal() sc.nextBigDecimal sc int C = 100; C 100 BigDecimal bA = new BigDecimal(A); bA new BigDecimal(A) BigDecimal bC = new BigDecimal(C); bC new BigDecimal(C) B = B.multiply(bC) B B.multiply(bC) B.multiply B bC BigDecimal pop = bA.multiply(B); pop bA.multiply(B) bA.multiply bA B pop = pop.divide(bC) pop pop.divide(bC) pop.divide pop bC pop = pop.setScale(0, BigDecimal.ROUND_DOWN) pop pop.setScale(0, BigDecimal.ROUND_DOWN) pop.setScale pop 0 BigDecimal.ROUND_DOWN BigDecimal BigDecimal.ROUND_DOWN System.out.println(pop) System.out.println System.out System System.out pop String[] args args 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);
	}
} 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);
	}
} Main
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);
	}
}