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

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
      	double B = sc.nextDouble();
      	BigDecimal A2 = new BigDecimal(Long.toString(A));
      	BigDecimal B2 = new BigDecimal(Double.toString(B));
      	BigDecimal value = A2.multiply(B2);
      	BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN);
      	//String str = Double.toString(ans2);
      	System.out.println(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);
        long A = sc.nextLong();
      	double B = sc.nextDouble();
      	BigDecimal A2 = new BigDecimal(Long.toString(A));
      	BigDecimal B2 = new BigDecimal(Double.toString(B));
      	BigDecimal value = A2.multiply(B2);
      	BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN);
      	//String str = Double.toString(ans2);
      	System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
      	double B = sc.nextDouble();
      	BigDecimal A2 = new BigDecimal(Long.toString(A));
      	BigDecimal B2 = new BigDecimal(Double.toString(B));
      	BigDecimal value = A2.multiply(B2);
      	BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN);
      	//String str = Double.toString(ans2);
      	System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
      	double B = sc.nextDouble();
      	BigDecimal A2 = new BigDecimal(Long.toString(A));
      	BigDecimal B2 = new BigDecimal(Double.toString(B));
      	BigDecimal value = A2.multiply(B2);
      	BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN);
      	//String str = Double.toString(ans2);
      	System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long A = sc.nextLong(); A sc.nextLong() sc.nextLong sc double B = sc.nextDouble(); B sc.nextDouble() sc.nextDouble sc BigDecimal A2 = new BigDecimal(Long.toString(A)); A2 new BigDecimal(Long.toString(A)) BigDecimal B2 = new BigDecimal(Double.toString(B)); B2 new BigDecimal(Double.toString(B)) BigDecimal value = A2.multiply(B2); value A2.multiply(B2) A2.multiply A2 B2 BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN); ans value.setScale(0, BigDecimal.ROUND_DOWN) value.setScale value 0 BigDecimal.ROUND_DOWN BigDecimal BigDecimal.ROUND_DOWN System.out.println(ans) System.out.println 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);
        long A = sc.nextLong();
      	double B = sc.nextDouble();
      	BigDecimal A2 = new BigDecimal(Long.toString(A));
      	BigDecimal B2 = new BigDecimal(Double.toString(B));
      	BigDecimal value = A2.multiply(B2);
      	BigDecimal ans = value.setScale(0, BigDecimal.ROUND_DOWN);
      	//String str = Double.toString(ans2);
      	System.out.println(ans);
    }
}