#include <iostream>
using namespace std;

#include <boost/program_options.hpp>
using namespace boost::program_options;

int main(int argc, char** argv) {

   int x = 0;
   options_description desc("");
   desc.add_options()("x,x", value<int>(&x)->default_value(2), "x");
   
   variables_map vm;
   store(parse_command_line(argc, argv, desc), vm);
   notify(vm);
   return 0;
}