import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
 
 
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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*t);
		}
} import java.util.*; util.* java import java.math.RoundingMode; RoundingMode java.math import java.math.BigDecimal; BigDecimal java.math 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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*t);
		} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*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 int ans = 0; ans 0 while(n>0) {
			ans++;
			n-=x;
		} n>0 n 0 {
			ans++;
			n-=x;
		} ans++ ans n-=x n x System.out.println(ans*t) System.out.println System.out System System.out ans*t ans 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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*t);
		}
} Main
import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
 
 
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();
		int ans = 0;
		while(n>0) {
			ans++;
			n-=x;
		}
		System.out.println(ans*t);
		}
}