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);
}
}