#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("-O3")
using ld = long double;
const long long mod = 1e9 + 7;
const long long inf = 1e18;
const long long rk = 256;
const long long mod2 = 998244353;
const ld PI = 3.141592653589793;
ostream& operator<<(ostream& os, pair<long long, long long> const& x) {
  os << x.first << "," << x.second;
  return os;
}
template <class T>
ostream& operator<<(ostream& os, vector<T> const& x) {
  os << "{ ";
  for (auto& y : x) os << y << " ";
  return os << "}";
}
template <class T>
ostream& operator<<(ostream& os, set<T> const& x) {
  os << "{ ";
  for (auto& y : x) os << y << " ";
  return os << "}";
}
template <class Ch, class Tr, class Container>
basic_ostream<Ch, Tr>& operator<<(basic_ostream<Ch, Tr>& os,
                                  Container const& x) {
  os << "{ ";
  for (auto& y : x) os << y << " ";
  return os << "}";
}
template <class X, class Y>
ostream& operator<<(ostream& os, pair<X, Y> const& p) {
  return os << "[ " << p.first << ", " << p.second << "]";
}
const int mxn = 1e6 + 5;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  int n;
  cin >> n;
  vector<int> freq(n + 1, 0);
  vector<int> arr(n, 0);
  for (int i = 0; i < n; i++) cin >> arr[i];
  for (int ii = 1; ii <= n; ii++) {
    int i = ii - 1;
    int x = arr[i];
    if (x) {
      freq[max(ii - x, 0)]--;
      freq[ii]++;
    }
  }
  for (int i = 1; i <= n; i++) {
    freq[i] += freq[i - 1];
  }
  int cnt = 0;
  for (int i = 1; i <= n; i++) {
    if (freq[i] >= 0) {
      cnt++;
    }
  }
  cout << cnt << '\n';
  return 0;
}
