text: #include <boost/math/common_factor.hpp>
  #include <iostream>
  
  // c++ greatest common divisor
  // TODO: c++ todo in sub folder
  int main( ) {
     std::cout << "The least common multiple of 12 and 18 is " << 
        boost::math::lcm( 12 , 18 ) << " ,\n"
        << "and the greatest common divisor " << boost::math::gcd( 12 , 18 ) << " !" << std::endl ;
     return 0 ;
     // TODO: more todo
  }