import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    } main {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    } 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 time; time if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        } n % x == 0 n % x n x 0 {
            time = n / x * t;
        } time = n / x * t time n / x * t n / x n x t {
            time = (n / x + 1) * t;
        } time = (n / x + 1) * t time (n / x + 1) * t (n / x + 1) n / x n x 1 t System.out.println(time) System.out.println System.out System System.out time String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int time;
        
        if(n % x == 0){
            time = n / x * t;
        } else {
            time = (n / x + 1) * t;
        }
        
        System.out.println(time);
    }
}