#include <bits/stdc++.h>

using namespace std;

int main(){
    int people;
    cin >> people;
    int dead = 0;
    // 1 = alive AND 0 = dead
    vector <int> alive(people, 1);
    for(int i=0; i<people; ++i){
        int leng;
        cin >> leng;
        for(int f=(i-1); f>((i-1)-leng); --f){
            if(f >= 0 && alive[f] == 1){
                alive[f] = 0;
                ++dead;
            }
        }
    }
    cout << people - dead << "\n";
    return 0;
}