import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    }
    System.out.println(ans);
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    }
    System.out.println(ans);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *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 ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *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 ans; ans if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    } n%x == 0 n%x n x 0 {
      ans = (n/x) * t;
    } ans = (n/x) * t ans (n/x) * t (n/x) n x t {
      int m =  n / x;
      ans = (m+1) *t;
    } int m =  n / x; m n / x n x ans = (m+1) *t ans (m+1) *t (m+1) m 1 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){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    }
    System.out.println(ans);
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    }
    System.out.println(ans);
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    int ans;
    if (n%x == 0){
      ans = (n/x) * t;
    }else{
      int m =  n / x;
      ans = (m+1) *t;
    }
    System.out.println(ans);
  }
}