import java.io.*;
import java.util.*;
import java.lang.*;
import java.math.*;
  public class misol
  {
   public static void main(String[]args)
    {
     Scanner sc=new Scanner(System.in);
      int n=sc.nextInt();
      BigInteger[] a=new BigInteger[22];
      BigInteger s=new BigInteger("1");
      a[0]=new BigInteger("1");
      a[1]=new BigInteger("1");
      for(int i=2;i<=n;i++)
      {
        s=s.multiply(new BigInteger(Integer.toString(i)));
        a[i]=s;
      }
    s=new BigInteger("0");
    if (n>2)
    {
        for (int i=0;i<=n-2;i++)
            s=s.add(a[n].divide(a[i]));

        System.out.println(s);
    }
    else
    {
    if(n==2){System.out.println("2");}
    }
  }
 }

Salom Hamdam sani shu misol utgan  yili echisha uringan
akansan misol oson,lekin ozginaqiyin joyi bor 3 soat bari
shu misol ustidaman uzi oson ekan javob chiqsa sanga yaraman bollarga salom ayt.

Hamdam koding hatosi shundaki 1<= n <= 21
n=1
Sani dasturing hech nima chiqarmaydi.
Shuni uchun
if(n==1)System.out.println("0");
qo'ysang AC olasan.
H'op bo'pdi yozib tur man 6-kun,bozor kuni internetdaman