main.cpp

#include <fstream>
#include <iostream>
#include <iterator>

using namespace std;

template <typename Iter>
inline void safe_advance(Iter &i, const Iter &end, std::size_t steps)
{
  while (steps-- > 0)
  {
    if (i != end)
      ++i;
    else
      return;
  }
}

int main()
{
  typedef istreambuf_iterator<char> char_input;
  {
    static std::ifstream fin("1.txt");
    std::cin.rdbuf(fin.rdbuf());
  }

  for (char_input j(cin), end; j != end; safe_advance(j, end, 2))
    cout << *j;
  cout << endl;
}