import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
 public class Main
 {
 	public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	}
 } import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.*; util.* java public class Main
 {
 	public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	}
 } Main public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	} main {
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	} Scanner sc=new Scanner (System.in); sc new Scanner (System.in) int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc int x=sc.nextInt(); x sc.nextInt() sc.nextInt sc int t=sc.nextInt(); t sc.nextInt() sc.nextInt sc if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t); n%x==0 n%x n x 0 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)*t)+t) System.out.println System.out System System.out ((n/x)*t)+t ((n/x)*t) (n/x) n x t t String[]args args public class Main
 {
 	public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	}
 } public class Main
 {
 	public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	}
 } Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
 public class Main
 {
 	public static void main(String[]args)
 	{
 		Scanner sc=new Scanner (System.in);
 		int n=sc.nextInt();
 		int x=sc.nextInt();
 		int t=sc.nextInt();
 		if(n%x==0)
 			System.out.println((n/x)*t);
 		else
 			System.out.println(((n/x)*t)+t);
 	}
 }