

import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    }
} import java.util.*; util.* java import java.lang.*; lang.* java import java.io.*; io.* java public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    }
} Main public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    } main {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    } Scanner s = new Scanner(System.in); s new Scanner(System.in) int n = s.nextInt(); n s.nextInt() s.nextInt s int x =s.nextInt(); x s.nextInt() s.nextInt s int t = s.nextInt(); t s.nextInt() s.nextInt s int q; q if(n%x==0)
            q = n/x;
        else
            q = n/x+1; n%x==0 n%x n x 0 q = n/x q n/x n x q = n/x+1 q n/x+1 n/x n x 1 System.out.println(q*t) System.out.println System.out System System.out q*t q t String[] args args public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    }
} public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    }
} Main


import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*t);
    }
}