#include <iostream>
#include<fstream>

using namespace std;


int x,r;
ifstream f ("fractii.in");
ofstream g ("fractii.out");

int fr(int n)
{
   for (int i=1;i<=n;i++)
   {
        if (i%n != 0)
        {
         r++;
        }

   }
}


int main()
{

cin>>x;
for(int i=1;i<=x;i++)
  fr(x);

cout<<r;

    return 0;
}