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

surplus = []
deficit = []

for i in range(n):
    diff = b[i] - 1
    if diff > 0:
        surplus.append([i, diff])
    elif diff < 0:
        deficit.append([i, -diff])

surplus.sort()
deficit.sort()

s_idx = d_idx = 0
ans = 0

while s_idx < len(surplus) and d_idx < len(deficit):
    s_pos, s_cnt = surplus[s_idx]
    d_pos, d_cnt = deficit[d_idx]
    t = min(s_cnt, d_cnt)
    ans += t * abs(s_pos - d_pos)
    if s_cnt == t:
        s_idx += 1
    else:
        surplus[s_idx][1] = s_cnt - t
    if d_cnt == t:
        d_idx += 1
    else:
        deficit[d_idx][1] = d_cnt - t

print(ans)