import java.util.Scanner;

public class Main {

	public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	}

	public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	}


	// ************************************
	// Common
	// ************************************

	private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	}

	public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	}


	// ************************************
	// Common
	// ************************************

	private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	}

} Main public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	} solve {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	} int joyo = n % x ; joyo n % x n x int ans = n / x ; ans n / x n x System.out.println((ans * t) + (joyo != 0?t:0)) System.out.println System.out System System.out (ans * t) + (joyo != 0?t:0) (ans * t) ans t (joyo != 0?t:0) joyo != 0 joyo 0 t 0 int n n int x x int t t public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	} main {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	} long start = System.currentTimeMillis(); start System.currentTimeMillis() System.currentTimeMillis System Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		} {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		} scanner.close() scanner.close scanner {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} 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 scanner.nextLine() scanner.nextLine scanner solve(n, x, t) solve n x t long end = System.currentTimeMillis(); end System.currentTimeMillis() System.currentTimeMillis System String[] args args private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	} changeArrayStringToInt {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	} String[] strArray = line.split(" "); strArray line.split(" ") line.split line " " int[] intArray = new int[strArray.length]; intArray new int[strArray.length] strArray.length strArray strArray.length for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		} int i = 0; int i = 0; i 0 i < intArray.length i intArray.length intArray intArray.length i++ i++ i {
			intArray[i] = Integer.parseInt(strArray[i]);
		} {
			intArray[i] = Integer.parseInt(strArray[i]);
		} intArray[i] = Integer.parseInt(strArray[i]) intArray[i] intArray i Integer.parseInt(strArray[i]) Integer.parseInt Integer strArray[i] strArray i return intArray; intArray String line line public class Main {

	public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	}

	public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	}


	// ************************************
	// Common
	// ************************************

	private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	}

} public class Main {

	public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	}

	public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	}


	// ************************************
	// Common
	// ************************************

	private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	}

} Main
import java.util.Scanner;

public class Main {

	public static void solve (int n, int x, int t) {

		int joyo = n % x ;
		int ans = n / x ;

		System.out.println((ans * t) + (joyo != 0?t:0));

	}

	public static void main(String[] args) {

		long start = System.currentTimeMillis();
	    // 引数で標準入力System.inを指定する
	    Scanner scanner = new Scanner(System.in);
		try {

		    // 1行目を取得(a)
			int n  = scanner.nextInt();
			int x  = scanner.nextInt();
			int t  = scanner.nextInt();
			scanner.nextLine();

			solve(n, x, t);

		} finally {
		    // Scannerクラスのインスタンスをクローズ
		    scanner.close();
		}
		long end = System.currentTimeMillis();
		// System.out.println((end - start) );
	}


	// ************************************
	// Common
	// ************************************

	private static final int[] changeArrayStringToInt(String line) {

		String[] strArray = line.split(" ");

		int[] intArray = new int[strArray.length];

		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = Integer.parseInt(strArray[i]);
		}
		return intArray;
	}

}
