//---------------------------------------------------------------------------

#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused
#include <iostream.h>
int main(int argc, char* argv[])
{
  int i,a[10010];
  a[0]=1;
  for (i=1;i<=10000;i++)
    a[i]=a[i-1]+9*i-3;

  while (cin>>i)
    cout<<a[i]-5*i<<endl;
  return 0;
}
//---------------------------------------------------------------------------