A zero-indexed array ```arr``` consisting of n integers is given. The dominator of array ```arr``` is the value that occurs in more than half of the elements of ```arr```.
For example, consider array ```arr``` such that ```arr = [3,4,3,2,3,1,3,3]``` The dominator of ```arr``` is 3 because it occurs in 5 out of 8 elements of ```arr``` and 5 is more than a half of 8.
Write a function ```dominator(arr)``` that, given a zero-indexed array ```arr``` consisting of n integers, returns the dominator of ```arr```. The function should return −1 if array does not have a dominator. All values in ```arr``` will be >=0.
from collections import Counter

def dominator(arr):
    n = Counter(arr).most_common(1)
    return n[0][0] if n and n[0][1] > len(arr)//2 else -1
from collections import Counter

def dominator(arr):
    n = Counter(arr).most_common(1)
    return n[0][0] if n and n[0][1] > len(arr)//2 else -1