import java.util.Scanner;

public class Main {
    public int getTime(int n, int x, int t) {
        if (n % x == 0) return (n / x) * t;
        else return (n / x + 1) * t;
    }

    public static void main(String[] args) throws Exception {
        Main solution = new Main();

        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();

        int answer = solution.getTime(n, x, t);
        System.out.println(answer);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz