n, *r = map(int, open(0).read().split())
a = [[]for _ in [0] * (n + 1)]
for i in range(n - 1):
    a[r[i]] += i + 1,
ans = 0
i = j = n
while i > 1:
    ans += 1
    m = n
    for k in range(i, j + 1):
        m = min(m, min(a[k] + [n]))
    j = i - 1
    i = m
print(ans)