I found an interesting problem on https://codeforces.com/problemset/problem/892/B:
Hands that shed innocent blood!

There are n guilty people in a line, the i-th of them holds a claw with length L_{i}. The bell rings and every person kills some of people in front of him. All people kill others at the same time. Namely, the i-th person kills the j-th person if and only if j < i and j ≥ i - L_{i}.

You are given lengths of the claws. You need to find the total number of alive people after the bell rings.


-----Input-----

The first line contains one integer n (1 ≤ n ≤ 10^6) — the number of guilty people.

Second line contains n space-separated integers L_1, L_2, ..., L_{n} (0 ≤ L_{i} ≤ 10^9), where L_{i} is the length of the i-th person's claw.


-----Output-----

Print one integer — the total number of alive people after the bell rings.


-----Examples-----
Input
4
0 1 0 10

Output
1

Input
2
0 0

Output
2

Input
10
1 1 3 0 0 0 2 1 0 3

Output
3



-----Note-----

In first sample the last person kills everyone in front of him.

I tried it in Python, but could not do it. Can you solve it?
n = int(input())
l = [int(x) for x in input().split(" ")]
s = [1 for i in range(n)]

p = n-1
q = n-1

while p>0:
    while q>p-l[p] and q>0:
        q -= 1
        s[q] = 0
    p-=1
    q = min(p,q)

print(sum(s))