B. Wrath
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

Hands that shed innocent blood!

There are n guilty people in a line, the i-th of them holds a claw with length Li. 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 - Li.

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 ≤ 106) — the number of guilty people.

Second line contains n space-separated integers L1, L2, ..., Ln (0 ≤ Li ≤ 109), where Li 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
40 1 0 10
Output
1
Input
20 0
Output
2
Input
101 1 3 0 0 0 2 1 0 3
Output
3
Note

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