// O(n^2) のTLE解を unordered_map にして、定数倍高速化したやつ
#include <bits/stdc++.h>
using namespace std;

int solve() {
  int n;
  cin >> n;
  vector<int> A(n);
  for (int i = 0; i < n; i++) cin >> A[i];

  unordered_map<int, int> q1, q2;
  auto &cur = q1;
  auto &nex = q2;

  cur[0] = 0;

  for (int i = 0; i < n; i++) {
    for (auto cl : cur) {
      int c = cl.first;
      int l = cl.second;

      if (l < A[i]) {
        if (nex.count(c) == 0 || nex[c] > A[i]) {
          nex[c] = A[i];
        }
      }
      if (nex.count(c + 1) == 0 || nex[c + 1] > l + 1) {
        nex[c + 1] = l + 1;
      }
    }
    swap(cur, nex);
    nex.clear();
  }

  int ans = 1e9;
  for (auto cl : cur) {
    ans = min(ans, cl.first);
  }
  return ans;
  //return cur.begin()->fst;  // mapならこちら
}

int main() {
  cin.tie(nullptr); ios::sync_with_stdio(false);
  cout << solve() << endl;
  return 0;
}