import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	}

} import java.util.Scanner; Scanner java.util import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	} 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 count = 0; count 0 int count2 = 0; count2 0 while (count < n){
			count += x;
			count2 += t;
		} count < n count n {
			count += x;
			count2 += t;
		} count += x count x count2 += t count2 t System.out.println(count2) System.out.println System.out System System.out count2 String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	}

} Main
import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int count = 0;
		int count2 = 0;
		while (count < n){
			count += x;
			count2 += t;
		}
		System.out.println(count2);
	}

}
