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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(T);
    }
} 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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(T);
    } main {
    	Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();
        int count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(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 count = 1; count 1 while (N > X) {
        	N -= X;
        	count++;
        } N > X N X {
        	N -= X;
        	count++;
        } N -= X N X count++ count T = T * count T T * count T count System.out.println(T) System.out.println System.out System System.out 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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(T);
    }
} 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 count = 1;
      
        while (N > X) {
        	N -= X;
        	count++;
        }
      
        T = T * count;
        System.out.println(T);
    }
}