import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    } 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 num1=N/X; num1 N/X N X if(N%X>=1){
            num1+=1;
        } N%X>=1 N%X N X 1 {
            num1+=1;
        } num1+=1 num1 1 int ans =num1*T; ans num1*T num1 T 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 {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int N=sc.nextInt();
        int X=sc.nextInt();
        int T=sc.nextInt();
        
        int num1=N/X;
        if(N%X>=1){
            num1+=1;
        }
        
        int ans =num1*T;
        
        System.out.println(ans);
    }
}
