

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	}

} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.StringTokenizer; StringTokenizer java.util public class Main {

	public static void main(String[] args)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	}

} Main public static void main(String[] args)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	} main {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st = new StringTokenizer(br.readLine()); st new StringTokenizer(br.readLine()) int n = Integer.parseInt(st.nextToken()); n Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int x = Integer.parseInt(st.nextToken()); x Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int t = Integer.parseInt(st.nextToken()); t Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int ans=0; ans 0 while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        } n>0 n 0 {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        } ans+=t ans t n=n>=x?n-x:0 n n>=x?n-x:0 n>=x n x n-x n x 0 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)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	}

} public class Main {

	public static void main(String[] args)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	}

} Main


import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args)throws Exception {

		 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		 StringTokenizer st = new StringTokenizer(br.readLine());
		 int n = Integer.parseInt(st.nextToken());
		 int x = Integer.parseInt(st.nextToken());
		 int t = Integer.parseInt(st.nextToken());
	        
	        int ans=0;
	        while(n>0) {
	        	ans+=t;
	        	n=n>=x?n-x:0;
	        }
	        System.out.println(ans);
	        
	}

}
