  We study symplectic structures on filiform Lie algebras -- nilpotent Lie
algebras of the maximal length of the descending central sequence. In the
present article we classify the Lie algebras with the structure relations of
the following form: $$[e_i,e_j]=(j-i)e_{i+j}+\sum_{l{=}1}c_{ij}^l e_{i+j+l},
i+j \le n.$$ In even dimensions the subspace of symplectic Lie algebras has the
codimension one.
