import java.util.Scanner;
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 set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * T);
    } 
} 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();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * 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 set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * T);
    } main {
        Scanner sc= new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * 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 set = (N / X); set (N / X) N X if(N % X >= 1) set++; N % X >= 1 N % X N X 1 set++ set System.out.println(set * T) System.out.println System.out System System.out set * T set 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 set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * 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 set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * T);
    } 
} Main
import java.util.Scanner;
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 set = (N / X);
        if(N % X >= 1) set++;
      System.out.println(set * T);
    } 
}