import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    // printTestValue();
    // abc170_d();
    // abc169_b();
    abc169_c();
  }

  public static void abc169_c() {
    try (Scanner sc = new Scanner(System.in)) {
      BigDecimal a = new BigDecimal(sc.next());
      BigDecimal b = new BigDecimal(sc.next());

      System.out.println(a.multiply(b).setScale(0, RoundingMode.DOWN));

    } catch (Exception e) {
      System.out.println("エラー" + e);
    }
  }
}
/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