A majority element is an element that makes up more than half of the items in an array. Given a integers array, find the majority element. If there is no majority element, return -1. Do this in O(N) time and O(1) space.

Example 1:

Input: [1,2,5,9,5,9,5,5,5]

Output: 5

Example 2:

Input: [3,2]

Output: -1

Example 3:

Input: [2,2,1,1,1,2,2]

Output: 2