N = int(input())
A = list(map(int, input().split()))
S = sum(A)
i = 1

while True:
    if (i+1) ** 2 > S:
        break
    i += 1
    
pyramid = [j for j in range(1, i+1)] + [j for j in range(i-1, 0, -1)]

if len(pyramid) > len(A):
    A += [0] * (len(pyramid) - len(A))
else:
    pyramid += [0] * (len(A) - len(pyramid))

ans = sum(A_i - pyramid_i for A_i, pyramid_i in zip(A, pyramid) if A_i > pyramid_i)
print(ans)