#include <iostream>
using namespace std;

int main()
{
  int n, k, m;
  bool through[10000], mem[10000];
  cin >> n;
  k=1;
  through[0]=1;
  for( int i=1; i<n; ++i )
  {
    m=1;
    for(int j=k+1; j>1; j>>=1)m+=j&1;
    if(n<k+m || 0<through[k+m-1])
    {
      if(k+m==2){m=-1; i=n;}
      k-=m;
      through[k]=1;
    }
    else if( n==k+m )
    {
      m=i; i=n;
    }
    else
    {
      k+=m;
      through[k]=1;
    }
  }
  cout << m << endl;
  return 0;
}