//package basics.AtCoders;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
} Main public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    } main {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    } Scanner s =new Scanner(System.in); s new Scanner(System.in) int N = s.nextInt(); N s.nextInt() s.nextInt s int X = s.nextInt(); X s.nextInt() s.nextInt s int T = s.nextInt(); T s.nextInt() s.nextInt s if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        } N%X==0 N%X N X 0 {
            System.out.println(N/X*T);
        } System.out.println(N/X*T) System.out.println System.out System System.out N/X*T N/X N X T {
            System.out.println((N/X+1)*T);
        } System.out.println((N/X+1)*T) System.out.println System.out System System.out (N/X+1)*T (N/X+1) N/X N X 1 T String[] args args public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
} public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
} Main
//package basics.AtCoders;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
}
