import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        //一个整数 == 4个字节
        //n MB = n * 1024 * 1024 B
        //n MB = n * 1024 * 1024 / 4 个整数
        //输入内存容量nMB,输出能存放多少整数
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n * 1024 * 1024 / 4);
    }
}