import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    } main {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n=sc.nextInt() n sc.nextInt() sc.nextInt sc x=sc.nextInt() x sc.nextInt() sc.nextInt sc t=sc.nextInt(); t sc.nextInt() sc.nextInt sc int sum=0; sum 0 while(n>0){
            n = n-x;
            sum = sum + t;
        } n>0 n 0 {
            n = n-x;
            sum = sum + t;
        } n = n-x n n-x n x sum = sum + t sum sum + t sum t System.out.println(sum) System.out.println System.out System System.out sum String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),x=sc.nextInt(),t=sc.nextInt();
        int sum=0;
        while(n>0){
            n = n-x;
            sum = sum + t;
        }
        System.out.println(sum);
    }
}