import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  } main {
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String line = sc.nextLine(); line sc.nextLine() sc.nextLine sc String info[] = new String[3]; info new String[3] 3 info = line.split(" ", 0) info line.split(" ", 0) line.split line " " 0 int n = Integer.parseInt(info[0]); n Integer.parseInt(info[0]) Integer.parseInt Integer info[0] info 0 int x = Integer.parseInt(info[1]); x Integer.parseInt(info[1]) Integer.parseInt Integer info[1] info 1 int t = Integer.parseInt(info[2]); t Integer.parseInt(info[2]) Integer.parseInt Integer info[2] info 2 if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    } n % x == 0 n % x n x 0 {
		System.out.println(n / x * t);
    } System.out.println(n / x * t) System.out.println System.out System System.out n / x * t n / x n x t {
      	System.out.println((n / x + 1)* t);
    } System.out.println((n / x + 1)* t) System.out.println System.out System System.out (n / x + 1)* t (n / x + 1) n / x n x 1 t String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  }
} Main
import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    String info[] = new String[3];
    info = line.split(" ", 0);
    int n = Integer.parseInt(info[0]);
    int x = Integer.parseInt(info[1]);
    int t = Integer.parseInt(info[2]);
    
    if(n % x == 0){
		System.out.println(n / x * t);
    }else{
      	System.out.println((n / x + 1)* t);
    }
  }
}