【Codeforces Round #446 (Div. 2) B】Wrath

#include <bits/stdc++.h>
using namespace std;

const int N = 1e6;
int a[N+10],n;
int isdead[N+10];

int main(){
    #ifdef LOCAL_DEFINE
        freopen("F:\\c++source\\rush_in.txt", "r", stdin);
    #endif
    scanf("%d",&n);
    for (int i = 1;i <= n;i++)
        scanf("%d",&a[i]);
    reverse(a+1,a+1+n);
    isdead[1] = 0;
    int now = 1 + a[1];
    for (int i = 2;i <= n;i++){
        if (now>=i){
            isdead[i] = 1;
        }
        now = max(now,i+a[i]);
    }
    int cnt = 0;
    for (int i = 1;i <= n;i++)
        if (!isdead[i]){
            cnt++;
        }
    printf("%d\n",cnt);
    
    return 0;
}