import 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	}
} import java.util.*; util.* java 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	}
} 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		int time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	} 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 time = 0; time 0 for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		} int i = 1; int i = 1; i 1 i <= 1000 i 1000 i++ i++ i {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		} {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		} time += T time T N -= X N X if(N <= 0) {
				System.out.println(time);
				break;
			} N <= 0 N 0 {
				System.out.println(time);
				break;
			} System.out.println(time) System.out.println System.out System System.out time break; 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	}
} 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	}
} Main
import 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 time = 0;
		
		for(int i = 1; i <= 1000; i++) {
			time += T;
			N -= X;

			if(N <= 0) {
				System.out.println(time);
				break;
			}
		}
		
	}
}