#include <synaps/arithm/gmp.h>
#include <synaps/upol/UPolDse.h>
#include <synaps/usolve/Aberth.h>

int main(int argc, char** argv) 
{
  using std::cout;
  using std::endl;
  UPolDse<QQ> p("1"), l("x-1");
  for(unsigned i=0;i<20;i++) {p*=l;l-=QQ(1);}
  cout<<p<<endl;

  ...
}