In quidrilateral $$ABCD$$, The diagonals $$\overline{AC}$$ and $$\overline{BD}$$ intersect at the point $$O$$, and the following four sets of conditions are given:①$$\overline{AB}\parallel\overline{CD},\overline{AD}\parallel\overline{BC}$$;
②$$AB = CD,AD = BC$$;
③$$AO = CO,BO = DO$$;
④$$\overline{AB}\parallel\overline{CD},AD = BC$$.
The number of sets which must be able to deduce that this quadrilateral is a parallelogram is ( ).