from collections import deque


N = int(input())
R = list(map(int, input().split()))
edge = [-1 for _ in range(N)]
for i in range(N - 1):
    for j in range(R[i] - 1, i, -1):
        if edge[j] == -1:
            edge[j] = i
        else:
            break

now = N - 1
cnt = 0
while now != 0:
    cnt += 1
    now = edge[now]
print(cnt)