/** @file list4205.cpp */
/** Listing 42-5. Negating the Middle Value in a Series of Integers */
#include <iostream>
#include <ostream>

#include "data.hpp"

int main()
{
  intvector data;
  read_data(data);
  intvector::const_iterator iter(data.begin());
  std::advance(iter, data.size() / 2); // move to middle of vector
  if (not data.empty())
    *iter = - *iter;
  write_data(data);
}