B. Jeff and Periodstime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputOne day Jeff got hold of an integer sequence a1, a2, ..., an of length n. The boy immediately decided to analyze the sequence. For that, he needs to find all values of x, for which these conditions hold:  x occurs in sequence a.  Consider all positions of numbers x in the sequence a (such i, that ai = x). These numbers, sorted in the increasing order, must form an arithmetic progression. Help Jeff, find all x that meet the problem conditions.InputThe first line contains integer n (1 ≤ n ≤ 105). The next line contains integers a1, a2, ..., an (1 ≤ ai ≤ 105). The numbers are separated by spaces.OutputIn the first line print integer t — the number of valid x. On each of the next t lines print two integers x and px, where x is current suitable value, px is the common difference between numbers in the progression (if x occurs exactly once in the sequence, px must equal 0). Print the pairs in the order of increasing x.ExamplesInput12Output12 0Input81 2 1 3 1 2 1 5Output41 22 43 05 0NoteIn the first test 2 occurs exactly once in the sequence, ergo p2 = 0.
Input12
Output12 0
['implementation', 'sortings', '*1300']