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

public class Main {

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  }
} Main public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  } main {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String[] input = br.readLine().split(" "); input br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int n = Integer.parseInt(input[0]); n Integer.parseInt(input[0]) Integer.parseInt Integer input[0] input 0 int x = Integer.parseInt(input[1]); x Integer.parseInt(input[1]) Integer.parseInt Integer input[1] input 1 int t = Integer.parseInt(input[2]); t Integer.parseInt(input[2]) Integer.parseInt Integer input[2] input 2 br.close() br.close br System.out.println((x + n - 1) / x * t) System.out.println System.out System System.out (x + n - 1) / x * t (x + n - 1) / x (x + n - 1) x + n x n 1 x t String[] args args public class Main {

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  }
} public class Main {

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] input = br.readLine().split(" ");
    int n = Integer.parseInt(input[0]);
    int x = Integer.parseInt(input[1]);
    int t = Integer.parseInt(input[2]);
    br.close();
    System.out.println((x + n - 1) / x * t);
  }
}