import java.util.Scanner;

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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    }
} import java.util.Scanner; Scanner 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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    }
} 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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        
        int sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    } 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 sumNum = 0; sumNum 0 int minTime = 0; minTime 0 while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        } n > sumNum n sumNum {
        	sumNum += x; 
        	minTime += t;
        } sumNum += x sumNum x minTime += t minTime t System.out.println(minTime) System.out.println System.out System System.out minTime 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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    }
} 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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    }
} Main
import java.util.Scanner;

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 sumNum = 0;
        int minTime = 0;
        
        while (n > sumNum) {
        	sumNum += x; 
        	minTime += t;
        }
        
        System.out.println(minTime);

    }
}