import random

def main():
    inputs = [input() for _ in range(2)]
    N = int(inputs[0])
    ingredients = [float(i) for i in inputs[1].split(' ')]

    for _ in range(N-1):
        curr_N = len(ingredients)
        index_x, index_y = random.sample(range(curr_N), 2)
        if index_x < index_y:
            index_x, index_y = index_y, index_x
        new_ingredient = (ingredients.pop(index_x) + ingredients.pop(index_y)) / 2.
        ingredients.append(new_ingredient)
    
    if len(ingredients) == 1:
        print(ingredients[0])

if __name__ == '__main__':
    main()