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

public class Main {
    public static void main(String []args) throws IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException 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 IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    }
} Main public static void main(String []args) throws IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    } 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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    } 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 sum=0; sum 0 while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        } N>0 N 0 {
            N-=X;
            sum+=T;
//            System.out.println(sum);
        } N-=X N X sum+=T sum T System.out.println(sum) System.out.println System.out System System.out sum String []args args public class Main {
    public static void main(String []args) throws IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    }
} public class Main {
    public static void main(String []args) throws IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    public static void main(String []args) throws IOException {
        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 sum=0;
        while (N>0){
            N-=X;
            sum+=T;
//            System.out.println(sum);
        }
        System.out.println(sum);
    }
}
