#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e15 + 15;
int main() {
  cin.tie(0);
  cout.tie(0);
  cin.sync_with_stdio(false);
  long long n, temp;
  vector<long long> v;
  cin >> n;
  while (n--) {
    cin >> temp;
    v.push_back(temp);
  }
  vector<long long> x(v.size(), -1);
  for (long long i = v.size() - 1; i >= 0; i--) {
    long long kill = i - v[i];
    kill = max(kill, 0LL);
    if (i && kill != i) x[kill] = max(x[kill], i);
  }
  set<long long> ms;
  long long killed = 0;
  for (long long i = 0; i < x.size(); i++) {
    if (x[i] != -1) {
      ms.insert(x[i]);
    }
    if (ms.find(i) != ms.end()) ms.erase(ms.find(i));
    if (ms.size()) killed++;
  }
  cout << x.size() - killed;
  return 0;
}
