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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	}

} 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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	}

} 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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		int m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	} 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 m=0; m 0 int ans=0; ans 0 while(0<N) {
			N = N - x;
			m++;
		} 0<N 0 N {
			N = N - x;
			m++;
		} N = N - x N N - x N x m++ m ans = t*m ans t*m t m System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc 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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	}

} 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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	}

} 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 m=0;
		int ans=0;
		
		while(0<N) {
			N = N - x;
			m++;
		}
		ans = t*m;
		System.out.println(ans);
		sc.close();
		
	}

}
