import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {

  static long n, m;
  static long ans;

  public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.PrintWriter; PrintWriter java.io public class Main {

  static long n, m;
  static long ans;

  public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  }
} Main static long n n m; m static long ans; ans public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  } main {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) String[] in = br.readLine().split(" "); in br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " n = Long.parseLong(in[0]) n Long.parseLong(in[0]) Long.parseLong Long in[0] in 0 m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0') m (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0') (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0') (in[1].charAt(0) - '0') * 100 (in[1].charAt(0) - '0') in[1].charAt(0) in[1].charAt in[1] in 1 0 '0' 100 (in[1].charAt(2) - '0') * 10 (in[1].charAt(2) - '0') in[1].charAt(2) in[1].charAt in[1] in 1 2 '0' 10 (in[1].charAt(3) - '0') in[1].charAt(3) in[1].charAt in[1] in 1 3 '0' br.close() br.close br out.println((m * n) / 100) out.println out (m * n) / 100 (m * n) m n 100 out.flush() out.flush out String[] args args public class Main {

  static long n, m;
  static long ans;

  public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  }
} public class Main {

  static long n, m;
  static long ans;

  public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {

  static long n, m;
  static long ans;

  public static void main(String[] args) throws Exception {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter out = new PrintWriter(System.out);

    String[] in = br.readLine().split(" ");
    n = Long.parseLong(in[0]);
    m = (in[1].charAt(0) - '0') * 100 + (in[1].charAt(2) - '0') * 10 + (in[1].charAt(3) - '0');

    br.close();

    out.println((m * n) / 100);

    out.flush();
  }
}
