n = int(input())
a = list(map(int, input().split()))
cnt = {}
for i in a:
    if i in cnt:
        cnt[i] += 1
    else:
        cnt[i] = 1
ans = 0
amari = []
for i in range(1,n+1):
    if i in cnt and cnt[i]>0:
        cnt[i] -= 1
    else:
        amari.append(i)
for i in amari:
    for d in range(1,n):
        if i+d in cnt and cnt[i+d]>0:
            ans += d
            cnt[i+d] -= 1
            break
        elif i-d in cnt and cnt[i-d]>0:
            ans += d
            cnt[i-d] -= 1
            break
print(ans)