import java.util.*;
import java.io.*;

public class Main {
    static StringBuilder sb;

    public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    }
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
    static StringBuilder sb;

    public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    }
} Main static StringBuilder sb; sb public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    } solve {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    } if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t); n % x == 0 n % x n x 0 sb.append(n / x * t) sb.append sb n / x * t n / x n x t sb.append((n / x + 1) * t) sb.append sb (n / x + 1) * t (n / x + 1) n / x n x 1 t int n n int x x int t t public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) PrintWriter pw = new PrintWriter(System.out); pw new PrintWriter(System.out) sb = new StringBuilder() sb new StringBuilder() 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 solve(n, x, t) solve n x t pw.print(sb) pw.print pw sb pw.flush() pw.flush pw sc.close() sc.close sc String[] args args public class Main {
    static StringBuilder sb;

    public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    }
} public class Main {
    static StringBuilder sb;

    public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    }
} Main
import java.util.*;
import java.io.*;

public class Main {
    static StringBuilder sb;

    public static void solve(int n, int x, int t) {
        if (n % x == 0) sb.append(n / x * t);
        else sb.append((n / x + 1) * t);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        sb = new StringBuilder();

        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();

        solve(n, x, t);

        pw.print(sb);
        pw.flush();
        sc.close();
    }
}