SETL

proc queens(n);
  count := 0;
  cols := {};
  diag1 := {};
  diag2 := {};

  proc solve(y);
    if y > n then
      count := count + 1;
    else
      for x in {1..n} - cols loop
        if not (x+y in diag1 or x-y in diag2) then
          cols with:= x;
          diag1 with:= x+y;
          diag2 with:= x-y;
          solve(y+1);
          cols less:= x;
          diag1 less:= x+y;
          diag2 less:= x-y;
        end if;
      end loop;
    end if;
  end proc;

  solve(1);
  return count;
end proc;

for n in [1..10] loop
  print(n, queens(n));
end loop;