import java.util.*; 
import java.io.*; 
import java.lang.Math; 
public class Main
{
     public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     }
} import java.util.*; util.* java import java.io.*; io.* java import java.lang.Math; Math java.lang public class Main
{
     public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     }
} Main public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     } main {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     } Scanner in=new Scanner(System.in); in new Scanner(System.in) int t t n n k k i i j=0 j 0 x; x double m; m n=in.nextInt() n in.nextInt() in.nextInt in x=in.nextInt() x in.nextInt() in.nextInt in t=in.nextInt() t in.nextInt() in.nextInt in m=Math.ceil((double)n/x) m Math.ceil((double)n/x) Math.ceil Math (double)n/x (double)n x m=m*t m m*t m t System.out.println((int)m) System.out.println System.out System System.out (int)m String []args args public class Main
{
     public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     }
} public class Main
{
     public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     }
} Main
import java.util.*; 
import java.io.*; 
import java.lang.Math; 
public class Main
{
     public static void main(String []args)
     {
         Scanner in=new Scanner(System.in);
        int t,n,k,i,j=0,x;
        double m;
        
            n=in.nextInt();
            x=in.nextInt();
            t=in.nextInt();
            m=Math.ceil((double)n/x);
            m=m*t;
            System.out.println((int)m);
            
        
     }
}
