1985 AIME Problem 5

A sequence of integers a_1, a_2, a_3, \ldots is chosen so that a_n = a_{n - 1} - a_{n - 2} for each n \ge 3. What is the sum of the first 2001 terms of this sequence if the sum of the first 1492 terms is 1985, and the sum of the first 1985 terms is 1492?

Leading zeroes must be inputted, so if your answer is 34, then input 034

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.