import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	}

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

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int x = scan.nextInt(); x scan.nextInt() scan.nextInt scan int t = scan.nextInt(); t scan.nextInt() scan.nextInt scan scan.close() scan.close scan int total = 1; total 1 while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		} true {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		} int a = x*total; a x*total x total if(n<=a) {
				break;
			} n<=a n a {
				break;
			} break; total++ total System.out.println(total*t) System.out.println System.out System System.out total*t total t String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	}

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

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		scan.close();

		int total = 1;


		while(true) {
			int a = x*total;
			if(n<=a) {
				break;
			}
			total++;
		}

		System.out.println(total*t);

	}

}
