n = int(input())
b = list(map(int, input().split()))

i = 1
p = 1
while True:
    i = i + 1
    p = i * i
    if p > sum(b):
        i = i - 1
        p = i * i
        break

to_top = [x for x in range(1, i+1)]
to_bottom = [y for y in range(i-1, 0, -1)]
pyramid = to_top + to_bottom

if len(pyramid) < len(b):
    pyramid = pyramid + [0] * (len(b)-len(pyramid))
if len(b) < len(pyramid):
    b = b + [0] * (len(pyramid)-len(b))

pb = 0
mb = 0
for j, k in zip(pyramid,b):
    if k > j:
        mb += k - j
    elif j > k:
        pb += j - k

if sum(b) > p:
    print(mb)
else:
    print(pb)