import java.util.Scanner;

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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	}
} import java.util.Scanner; Scanner 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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	}
} 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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	} 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 i = 0; i 0 for(;n > 0; i++) {
			n -= x;
		} ; n > 0 n 0 i++ i++ i {
			n -= x;
		} {
			n -= x;
		} n -= x n x System.out.println(i * t) System.out.println System.out System System.out i * t i t 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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	}
} 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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	}
} Main
import java.util.Scanner;

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 i = 0;
		for(;n > 0; i++) {
			n -= x;
		}
		System.out.println(i * t);
	}
}
