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

public class Main {
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.PrintWriter; PrintWriter 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 java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    } main {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    } BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in)); br new BufferedReader(new java.io.InputStreamReader(System.in)) PrintWriter pw = new PrintWriter(System.out); pw new PrintWriter(System.out) 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 result = 0; result 0 while(N > 0) {
            N = N - X;
            result += T;

        } N > 0 N 0 {
            N = N - X;
            result += T;

        } N = N - X N N - X N X result += T result T pw.println(result) pw.println pw result br.close() br.close br pw.close() pw.close pw String[] args args public class Main {
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    }
} public class Main {
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {
    
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        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 result = 0;

        while(N > 0) {
            N = N - X;
            result += T;

        }

        pw.println(result);
        br.close();
        pw.close();
    }
}