import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

N = int(readline())
A = np.array(read().split() + [0] * 110,np.int64)

S = A.sum()
max_ht = int(S ** .5)

answer = 10 ** 18
for h in range(max_ht+1):
    p = np.hstack([np.arange(1,h+1), np.arange(1,h)[::-1]])
    n = len(p)
    x = np.maximum(0, p - A[:n]).sum() + (S - h*h)
    if answer > x:
        answer = x

print(answer)