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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	}

} 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	}

} 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	} 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	} 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 int ans = 0; ans 0 if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		} X > N || X == N X > N X N X == N X N {
			ans = T;
		} ans = T ans T {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		} int ks = 1; ks 1 int nokori = N - X; nokori N - X N X int i = 0; i 0 while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			} nokori > 0 nokori 0 {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			} ks = ks + 1 ks ks + 1 ks 1 nokori = nokori - X nokori nokori - X nokori X i++ i ans = T * ks ans T * ks T ks System.out.println(ans) System.out.println System.out System System.out ans 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	}

} 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	}

} 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();

		int ans = 0;
		if(X > N || X == N) {
			ans = T;
		}else {
			int ks = 1; //たこ焼き焼く回数
			int nokori = N - X;
			int i = 0;
			while(nokori > 0) {
				ks = ks + 1;
				nokori = nokori - X;
				i++;
			}

			ans = T * ks;
		}

		System.out.println(ans);

	}

}