import java.util.Scanner;
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 kaisuu = 0;
    int nn = n;
    while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    }
    
    System.out.println(kaisuu*t);
  }
} import java.util.Scanner; Scanner java.util 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 kaisuu = 0;
    int nn = n;
    while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    }
    
    System.out.println(kaisuu*t);
  }
} 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 kaisuu = 0;
    int nn = n;
    while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    }
    
    System.out.println(kaisuu*t);
  } main {
    Scanner sc = new Scanner(System.in);

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

    int kaisuu = 0;
    int nn = n;
    while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    }
    
    System.out.println(kaisuu*t);
  } 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 kaisuu = 0; kaisuu 0 int nn = n; nn n while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    } nn > 0 nn 0 {
      nn = nn - x;
      kaisuu++;
    } nn = nn - x nn nn - x nn x kaisuu++ kaisuu System.out.println(kaisuu*t) System.out.println System.out System System.out kaisuu*t kaisuu t String[] args args
import java.util.Scanner;
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 kaisuu = 0;
    int nn = n;
    while(nn > 0) {
      nn = nn - x;
      kaisuu++;
    }
    
    System.out.println(kaisuu*t);
  }
}
