import java.util.*;
import java.lang.Math;
public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    }
} import java.util.*; util.* java import java.lang.Math; Math java.lang public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += 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 takoyaki = 0; takoyaki 0 int time = 0; time 0 while(takoyaki < N){
            takoyaki += X;
            time += T;
            } takoyaki < N takoyaki N {
            takoyaki += X;
            time += T;
            } takoyaki += X takoyaki X time += T time 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 {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    }
} Main
import java.util.*;
import java.lang.Math;
public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int takoyaki = 0;
        int time = 0;
        while(takoyaki < N){
            takoyaki += X;
            time += T;
            }
        System.out.println(time);
    }
}
