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

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.
'''input
1 2 3
4 5
6 7 8
45 9
'''

import sys
pow2 = pow              # for modular expo pow2(base, n, mod)
from math import *
from time import time
from collections import defaultdict
from bisect import bisect_right, bisect_left
from string import ascii_lowercase as lcs
from string import ascii_uppercase as ucs
from fractions import Fraction, gcd
from decimal import Decimal, getcontext
from itertools import product, permutations, combinations
#getcontext().prec = 500
#sys.setrecursionlimit(30000)

# What doesn't challenge you, makes you weaker.

mod = 10**9 + 7
INF = sys.maxint

raw_input = lambda: sys.stdin.readline().rstrip()
die = lambda : exit(0)
flush= lambda : sys.stdout.flush()

r_s = lambda: raw_input().strip()                   #read str
r_ss = lambda: raw_input().split()          #read stringss
r_i = lambda: int(raw_input())              #read int
r_is = lambda: map(int, raw_input().split())#read ints
r_f = lambda: float(raw_input())            #read float
r_fs = lambda: map(Decimal, raw_input().split()) #read floats

# For effieciently taking lots of queries with each query in a separate line
# having integer values separated by space. A 2d list is made with each row
# corresponding to line. Each row is a list with all the values.
# Use this for fast I/O by taking all input in one go.
r_qs = lambda: map(lambda s:map(int, s.split(' ')), sys.stdin.readlines())

'''-------------------------------------------------------------------'''

# Call it as dbg(varName=varName)
def dbg(**kwargs):
    print "Value of '" + kwargs.keys()[0] + "' is", kwargs[kwargs.keys()[0]]


def main():
    n = r_i()
    arr = r_is()
    arr = arr[::-1]
    val = arr[0]
    ans = 1
    for elem in arr[1:]:
        if val==0:
            ans += 1
        val = max(elem,val-1)
    print ans
if __name__ == '__main__':
    local = True
    # local = False
    if local:
        try:
            sys.stdin = open('input.txt')
            print 'Running at local.'
            for i in range(r_i()):
                main()
        except IOError:
            main()
    else:
        main()


