import java.util.Scanner;
class Main{
     public static void main(String args[]){
        Scanner stdin = new Scanner(System.in);
        int N = stdin.nextInt();
        int X = stdin.nextInt();
        int T = stdin.nextInt();
        int try_num = N / X;
        if (N % X != 0) try_num++;
        System.out.println(try_num * T);
    }
} import java.util.Scanner; Scanner java.util class Main{
     public static void main(String args[]){
        Scanner stdin = new Scanner(System.in);
        int N = stdin.nextInt();
        int X = stdin.nextInt();
        int T = stdin.nextInt();
        int try_num = N / X;
        if (N % X != 0) try_num++;
        System.out.println(try_num * T);
    }
} Main public static void main(String args[]){
        Scanner stdin = new Scanner(System.in);
        int N = stdin.nextInt();
        int X = stdin.nextInt();
        int T = stdin.nextInt();
        int try_num = N / X;
        if (N % X != 0) try_num++;
        System.out.println(try_num * T);
    } main {
        Scanner stdin = new Scanner(System.in);
        int N = stdin.nextInt();
        int X = stdin.nextInt();
        int T = stdin.nextInt();
        int try_num = N / X;
        if (N % X != 0) try_num++;
        System.out.println(try_num * T);
    } Scanner stdin = new Scanner(System.in); stdin new Scanner(System.in) int N = stdin.nextInt(); N stdin.nextInt() stdin.nextInt stdin int X = stdin.nextInt(); X stdin.nextInt() stdin.nextInt stdin int T = stdin.nextInt(); T stdin.nextInt() stdin.nextInt stdin int try_num = N / X; try_num N / X N X if (N % X != 0) try_num++; N % X != 0 N % X N X 0 try_num++ try_num System.out.println(try_num * T) System.out.println System.out System System.out try_num * T try_num T String args[] args
import java.util.Scanner;
class Main{
     public static void main(String args[]){
        Scanner stdin = new Scanner(System.in);
        int N = stdin.nextInt();
        int X = stdin.nextInt();
        int T = stdin.nextInt();
        int try_num = N / X;
        if (N % X != 0) try_num++;
        System.out.println(try_num * T);
    }
}