Codility Extreme Deviation (Contenga)

#!/usr/bin/python

def solution ( A ):
    sizeA = len(A)
  
    if sizeA == 0:
        return -1
  
    m = 0
    for elem in A:
        m += elem
    m = m / float(sizeA)
  
    index = 0
    dev = -1
    for i in range(sizeA):
        elem = A[i]
        contenga = -1
        
        contenga = abs(long(elem) - long(m))
        
        if contenga > dev:
            dev = contenga
            index = long(i)
  
    return index