For any sequence of real numbers $$A=(a_1,a_2,a_3,\ldots)$$, define $$\Delta A^{}_{}$$ to be the sequence $$(a_2-a_1,a_3-a_2,a_4-a_3,\ldots)$$, whose $$n^{th}$$ term is $$a_{n+1}-a_n^{}$$. Suppose that all of the terms of the sequence $$\Delta(\Delta A^{}_{})$$ are $$1^{}_{}$$, and that $$a_{19}=a_{92}^{}=0$$. Find $$a_1^{}$$.

(第一十届AIME1992 第8题)