N = int(input())
A = list(map(int,input().split()))
M = sum(A)
n = 1
while n**2<=M:
    n += 1
n -= 1
ans = M
for k in range(1,n+1):
    A1 = A+[0 for _ in range(200-N)]
    B = list(range(1,k+1))+list(range(1,k))[::-1]
    B1 = B+[0 for _ in range(200-len(B))]
    cnt = 0
    for i in range(200):
        cnt += max(A1[i]-B1[i],0)
    ans = min(ans,cnt)
print(ans)