One day Jeff got hold of an integer sequence a 1 , a 2 , ... , a n 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 a i = x ). These numbers, sorted in the increasing order, must form an arithmetic progression. Help Jeff, find all x that meet the problem conditions. The first line contains integer n (1 ≤ n ≤ 10 5 ) . The next line contains integers a 1 , a 2 , ... , a n (1 ≤ a i ≤ 10 5 ) . The numbers are separated by spaces. In the first line print integer t — the number of valid x . On each of the next t lines print two integers x and p x , where x is current suitable value, p x is the common difference between numbers in the progression (if x occurs exactly once in the sequence, p x must equal 0). Print the pairs in the order of increasing x . In the first test 2 occurs exactly once in the sequence, ergo p 2 = 0 .