import java.util.*;
import java.io.*;
public class Main
{
	public static void main(String args[]) throws IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	}
}		 import java.util.*; util.* java import java.io.*; io.* java public class Main
{
	public static void main(String args[]) throws IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	}
} Main public static void main(String args[]) throws IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	} main {
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	} BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n n x x t=0; t 0 String brr[]=br.readLine().split(" "); brr br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " n=Integer.parseInt(brr[0]) n Integer.parseInt(brr[0]) Integer.parseInt Integer brr[0] brr 0 x=Integer.parseInt(brr[1]) x Integer.parseInt(brr[1]) Integer.parseInt Integer brr[1] brr 1 t=Integer.parseInt(brr[2]) t Integer.parseInt(brr[2]) Integer.parseInt Integer brr[2] brr 2 long ans=0; ans 0 while(n>0)
		{
		ans+=t;
        n-=x;
		} n>0 n 0 {
		ans+=t;
        n-=x;
		} ans+=t ans t n-=x n x 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 IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	}
} public class Main
{
	public static void main(String args[]) throws IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	}
} Main
import java.util.*;
import java.io.*;
public class Main
{
	public static void main(String args[]) throws IOException
	{
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n,x,t=0;
		String brr[]=br.readLine().split(" ");
		n=Integer.parseInt(brr[0]);
		x=Integer.parseInt(brr[1]);
		t=Integer.parseInt(brr[2]);
		long ans=0;
		while(n>0)
		{
		ans+=t;
        n-=x;
		}
		System.out.println(ans);
	}
}		