import java.util.*;
import java.math.BigDecimal;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		BigDecimal A = sc.nextBigDecimal();
		BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5));
		BigDecimal ans = A.multiply(B);
		ans = ans.divide(BigDecimal.valueOf(100));
		ans = ans.setScale(0, BigDecimal.ROUND_DOWN);
		System.out.print(ans);
	}
} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		BigDecimal A = sc.nextBigDecimal();
		BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5));
		BigDecimal ans = A.multiply(B);
		ans = ans.divide(BigDecimal.valueOf(100));
		ans = ans.setScale(0, BigDecimal.ROUND_DOWN);
		System.out.print(ans);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		BigDecimal A = sc.nextBigDecimal();
		BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5));
		BigDecimal ans = A.multiply(B);
		ans = ans.divide(BigDecimal.valueOf(100));
		ans = ans.setScale(0, BigDecimal.ROUND_DOWN);
		System.out.print(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		BigDecimal A = sc.nextBigDecimal();
		BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5));
		BigDecimal ans = A.multiply(B);
		ans = ans.divide(BigDecimal.valueOf(100));
		ans = ans.setScale(0, BigDecimal.ROUND_DOWN);
		System.out.print(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) BigDecimal A = sc.nextBigDecimal(); A sc.nextBigDecimal() sc.nextBigDecimal sc BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5)); B new BigDecimal((int)(sc.nextDouble() * 100 + 0.5)) BigDecimal ans = A.multiply(B); ans A.multiply(B) A.multiply A B ans = ans.divide(BigDecimal.valueOf(100)) ans ans.divide(BigDecimal.valueOf(100)) ans.divide ans BigDecimal.valueOf(100) BigDecimal.valueOf BigDecimal 100 ans = ans.setScale(0, BigDecimal.ROUND_DOWN) ans ans.setScale(0, BigDecimal.ROUND_DOWN) ans.setScale ans 0 BigDecimal.ROUND_DOWN BigDecimal BigDecimal.ROUND_DOWN System.out.print(ans) System.out.print System.out System System.out ans String[] args args
import java.util.*;
import java.math.BigDecimal;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		BigDecimal A = sc.nextBigDecimal();
		BigDecimal B = new BigDecimal((int)(sc.nextDouble() * 100 + 0.5));
		BigDecimal ans = A.multiply(B);
		ans = ans.divide(BigDecimal.valueOf(100));
		ans = ans.setScale(0, BigDecimal.ROUND_DOWN);
		System.out.print(ans);
	}
}
