import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*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 m = n%x==0 ? n/x : n/x+1; m n%x==0 ? n/x : n/x+1 n%x==0 n%x n x 0 n/x n x n/x+1 n/x n x 1 System.out.println("" + (m*t)) System.out.println System.out System System.out "" + (m*t) "" (m*t) m t String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();
		int x = sc.nextInt();
		int t = sc.nextInt();
		
        int m = n%x==0 ? n/x : n/x+1;
      // 出力
		System.out.println("" + (m*t));
	}
}