This is a fairly short symphony, clocking in around 35 minutes. Apparently Tchaikovsky revisited the work some years after its initial composition, and thus we now have two versions -- the original (which ran 40 minutes) and the revised version, which the composer preferred. Critics and musicologists have argued compellingly for each version, but I tend to defer to the wishes of creators in such matters.
Here is Tchaikovsky's Symphony No. 2 in C minor.
Next week: The Third Symphony!