# include <cmath>
# include <cstdlib>
# include <iomanip>
# include <iostream>
#
using namespace std;
#
# include "middle_square.hpp"
#
//****************************************************************************80

long long int middle_square_next ( long long int s, long long int d )

//****************************************************************************80
//
//  Purpose:
//
//    middle_square_next() computes the next middle square random value.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    16 September 2022
//
//  Author:
//
//    John Burkardt
//
//  Reference:
//
//    Brian Hayes,
//    The Middle of the Square,
//    08 August 2022,
//    http://bit-player.org/
//
//  Input:
//
//    long long int s: the current seed, of no more than 2*D digits.
//
//    long long int d: HALF the number of digits.  
//    Typical values are 2, 3, or 4.
//
//  Output:
//
//    long long int middle_square, the next seed.
//
{
  long long int divisor;
  long long int r;
  long long ten = 10;
//
//  Square.
//
  r = s * s;
//
//  Drop last two digits.
//
  divisor = ( long long int ) ( pow ( ten, d ) );

  r = ( r / divisor );
//
//  Drop all but last four digits.
//
  divisor = ( long long int ) ( pow ( ten, 2 * d ) );

  r = ( r % divisor );

  return r;
}