Given an integer sequence of n elements ~a_1, a_2, …, a_n~. Find two indices i, j such that i < j and the difference ~a_j - a_i~ is the largest.

Input: from the standard device has the following format:

• The first line contains a positive integer n (2 ≤ n ≤ ~10^5~);
• The second line contains n positive integers ~a1, a2, …, an~ ~(0 ≤ a_i ≤ 10^9)~.

Output: Output to the standard device a single integer which is the largest value of the difference ~a_j - a_i~.

Exam:

Input 1

3 1 2 3

Output 1

2

Input 2

4
2 5 1 3

Output 2

3