#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using i3 = pair<int, ii>;
using li = pair<ll, int>;
using lii = pair<ll, ii>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<ii>;
using vpll = vector<pll>;
using vi3 = vector<i3>;
using vlii = vector<lii>;
const int N = 2e6 + 5;
const ll INF = 1e17 + 7;
const double eps = 1e-9, PI = acos(-1);
int n;
int ans[N];
void solve(int testCase) {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    ans[max(0, i - x - 1)]++;
    ans[i - 1]--;
  }
  int res = 0;
  for (int i = n; i >= 1; i--) {
    ans[i] += ans[i + 1];
    if (ans[i] >= 0) res++;
  }
  printf("%d\n", res);
}
int main() {
  int t = 1;
  for (int testCase = 1; testCase <= t; testCase++) {
    solve(testCase);
  }
  return 0;
}
