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