brick_length = int(input())
brick_list =  list(map( int, input().split() ))
total = sum(brick_list)




for i in range(100):
    if (i+1)**2 <= total < (i+2)**2:
        r = (i+1)
        break

pyramid = [ i+1 for i in range(r) ] + [ i+1 for i in range(r-1) ][::-1]

if brick_length < len(pyramid):
    d = len(pyramid) - brick_length
    brick_list =  brick_list  + [0] * d
    print(brick_list)

move = 0
for i in range(len(pyramid)):
    if pyramid[i] - brick_list[i] > 0:
        move += pyramid[i] - brick_list[i]
remove = total - r**2

print(move+remove)