import java.util.Scanner;

public class Main {
 
	public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
}
} import java.util.Scanner; Scanner java.util public class Main {
 
	public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
}
} Main public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
} main {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int N = scanner.nextInt(); N scanner.nextInt() scanner.nextInt scanner int X = scanner.nextInt(); X scanner.nextInt() scanner.nextInt scanner int T = scanner.nextInt(); T scanner.nextInt() scanner.nextInt scanner int amari = N % X; amari N % X N X if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    } amari != 0 amari 0 {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    } int sho = N / X + 1; sho N / X + 1 N / X N X 1 System.out.println(sho * T) System.out.println System.out System System.out sho * T sho T {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    } int sho = N / X; sho N / X N X System.out.println(sho * T) System.out.println System.out System System.out sho * T sho T String[] args args public class Main {
 
	public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
}
} public class Main {
 
	public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
}
} Main
import java.util.Scanner;

public class Main {
 
	public static void main(String[] args) {
 
		    Scanner scanner = new Scanner(System.in);
		    
		    int N = scanner.nextInt();
		    int X = scanner.nextInt();
		    int T = scanner.nextInt();
		    int amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * T);
		    }
}
}