import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	}
} 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 k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	}
} Main public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	} main {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc int k=sc.nextInt(); k sc.nextInt() sc.nextInt sc int t=sc.nextInt(); t sc.nextInt() sc.nextInt sc int s=0; s 0 if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        } n%k==0 n%k n k 0 {
        	s=n/k;
        } s=n/k s n/k n k {
        	s=n/k+1;
        } s=n/k+1 s n/k+1 n/k n k 1 System.out.println(t*s) System.out.println System.out System System.out t*s t s String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int k=sc.nextInt();
        int t=sc.nextInt();
        int s=0;
        if(n%k==0) {
        	s=n/k;
        }
        else {
        	s=n/k+1;
        }
        System.out.println(t*s);

		
	}
}