

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	}

} Main public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	} main {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String s[] = sc.nextLine().split(" "); s sc.nextLine().split(" ") sc.nextLine().split sc.nextLine() sc.nextLine sc " " int N = Integer.parseInt(s[0]); N Integer.parseInt(s[0]) Integer.parseInt Integer s[0] s 0 int X = Integer.parseInt(s[1]); X Integer.parseInt(s[1]) Integer.parseInt Integer s[1] s 1 int T = Integer.parseInt(s[2]); T Integer.parseInt(s[2]) Integer.parseInt Integer s[2] s 2 int result = 0; result 0 if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		} N % X == 0 N % X N X 0 {
			result = ( N / X ) * T ;
		} result = ( N / X ) * T result ( N / X ) * T ( N / X ) N X T {
			result = ( N / X + 1) * T;
		} result = ( N / X + 1) * T result ( N / X + 1) * T ( N / X + 1) N / X N X 1 T System.out.println(result ) System.out.println System.out System System.out result String[] args args public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	}

} public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	}

} Main


import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
		String s[] = sc.nextLine().split(" ");
		int N = Integer.parseInt(s[0]);
		int X = Integer.parseInt(s[1]);
		int T = Integer.parseInt(s[2]);

		int result = 0;
		if (N % X == 0) {
			result = ( N / X ) * T ;
		} else {
			result = ( N / X + 1) * T;
		}

		System.out.println(result );
	}

}
