import java.util.*;
import java.lang.*;
class Main
{
public static void main(String args[])
{
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
}
} import java.util.*; util.* java import java.lang.*; lang.* java class Main
{
public static void main(String args[])
{
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
}
} Main public static void main(String args[])
{
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
} main {
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
} Scanner obj=new Scanner(System.in); obj new Scanner(System.in) int n n x x t; t double c=0; c 0 n=obj.nextInt() n obj.nextInt() obj.nextInt obj x=obj.nextInt() x obj.nextInt() obj.nextInt obj t=obj.nextInt() t obj.nextInt() obj.nextInt obj double m=n; m n c=t*Math.ceil(m/x) c t*Math.ceil(m/x) t Math.ceil(m/x) Math.ceil Math m/x m x System.out.println((int)c) System.out.println System.out System System.out (int)c String args[] args
import java.util.*;
import java.lang.*;
class Main
{
public static void main(String args[])
{
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
}
}