n = int(input())
P = list(map(int, input().split()))
Q = list(range(1, n+1))
ans = 0
for i in reversed(range(n)):
    p = P[i]
    q = Q[i]
    if q > p:
        ans += i+1
    elif q < p:
        ans -= i+1
    else:
        continue
print(ans)