import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    abc176_a();
  }

  private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

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

  // int 2147483648 [ 2 * 10(9)]
  // long 9223372036854775808 [ 9 * 10(18)]

  public static int parseI(String value) {
    return Integer.parseInt(value);
  }

  public static long parseL(String value) {
    return Long.parseLong(value);
  }

  public static double parseD(String value) {
    return Double.parseDouble(value);
  }

  public static <T> String parseS(T value) {
    return String.valueOf(value);
  }

  public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  }

  public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  }

} import java.math.BigDecimal; BigDecimal java.math import java.math.BigInteger; BigInteger java.math import java.util.Scanner; Scanner java.util public class Main {

  public static void main(String[] args) {
    abc176_a();
  }

  private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

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

  // int 2147483648 [ 2 * 10(9)]
  // long 9223372036854775808 [ 9 * 10(18)]

  public static int parseI(String value) {
    return Integer.parseInt(value);
  }

  public static long parseL(String value) {
    return Long.parseLong(value);
  }

  public static double parseD(String value) {
    return Double.parseDouble(value);
  }

  public static <T> String parseS(T value) {
    return String.valueOf(value);
  }

  public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  }

  public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  }

} Main public static void main(String[] args) {
    abc176_a();
  } main {
    abc176_a();
  } abc176_a() abc176_a String[] args args private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

    } catch (Exception e) {
      System.out.println("エラー" + e);
    }
  } abc176_a {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

    } catch (Exception e) {
      System.out.println("エラー" + e);
    }
  } try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

    } catch (Exception e) {
      System.out.println("エラー" + e);
    } catch (Exception e) {
      System.out.println("エラー" + e);
    } Exception e {
      System.out.println("エラー" + e);
    } System.out.println("エラー" + e) System.out.println System.out System System.out "エラー" + e "エラー" e {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

    } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) double nAll = sc.nextInt(); nAll sc.nextInt() sc.nextInt sc double xOneTime = sc.nextInt(); xOneTime sc.nextInt() sc.nextInt sc int tMinute = sc.nextInt(); tMinute sc.nextInt() sc.nextInt sc System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute) System.out.println System.out System System.out (int) Math.ceil(nAll / xOneTime) * tMinute (int) Math.ceil(nAll / xOneTime) Math.ceil Math nAll / xOneTime nAll xOneTime tMinute public static int parseI(String value) {
    return Integer.parseInt(value);
  } parseI {
    return Integer.parseInt(value);
  } return Integer.parseInt(value); Integer.parseInt(value) Integer.parseInt Integer value String value value public static long parseL(String value) {
    return Long.parseLong(value);
  } parseL {
    return Long.parseLong(value);
  } return Long.parseLong(value); Long.parseLong(value) Long.parseLong Long value String value value public static double parseD(String value) {
    return Double.parseDouble(value);
  } parseD {
    return Double.parseDouble(value);
  } return Double.parseDouble(value); Double.parseDouble(value) Double.parseDouble Double value String value value public static <T> String parseS(T value) {
    return String.valueOf(value);
  } parseS {
    return String.valueOf(value);
  } return String.valueOf(value); String.valueOf(value) String.valueOf String value T value value public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  } parseBigD {
    return new BigDecimal(value);
  } return new BigDecimal(value); new BigDecimal(value) String value value public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  } parseBigI {
    return new BigInteger(value);
  } return new BigInteger(value); new BigInteger(value) String value value public class Main {

  public static void main(String[] args) {
    abc176_a();
  }

  private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

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

  // int 2147483648 [ 2 * 10(9)]
  // long 9223372036854775808 [ 9 * 10(18)]

  public static int parseI(String value) {
    return Integer.parseInt(value);
  }

  public static long parseL(String value) {
    return Long.parseLong(value);
  }

  public static double parseD(String value) {
    return Double.parseDouble(value);
  }

  public static <T> String parseS(T value) {
    return String.valueOf(value);
  }

  public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  }

  public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  }

} public class Main {

  public static void main(String[] args) {
    abc176_a();
  }

  private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

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

  // int 2147483648 [ 2 * 10(9)]
  // long 9223372036854775808 [ 9 * 10(18)]

  public static int parseI(String value) {
    return Integer.parseInt(value);
  }

  public static long parseL(String value) {
    return Long.parseLong(value);
  }

  public static double parseD(String value) {
    return Double.parseDouble(value);
  }

  public static <T> String parseS(T value) {
    return String.valueOf(value);
  }

  public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  }

  public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  }

} Main
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    abc176_a();
  }

  private static void abc176_a() {
    try (Scanner sc = new Scanner(System.in)) {
      double nAll = sc.nextInt();
      double xOneTime = sc.nextInt();
      int tMinute = sc.nextInt();

      System.out.println((int) Math.ceil(nAll / xOneTime) * tMinute);

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

  // int 2147483648 [ 2 * 10(9)]
  // long 9223372036854775808 [ 9 * 10(18)]

  public static int parseI(String value) {
    return Integer.parseInt(value);
  }

  public static long parseL(String value) {
    return Long.parseLong(value);
  }

  public static double parseD(String value) {
    return Double.parseDouble(value);
  }

  public static <T> String parseS(T value) {
    return String.valueOf(value);
  }

  public static BigDecimal parseBigD(String value) {
    return new BigDecimal(value);
  }

  public static BigInteger parseBigI(String value) {
    return new BigInteger(value);
  }

}
