#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>
#include <random>
#include <atcoder/lazysegtree>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
    return vector<vector<T>>(n, vector<T>(m, v));
}

template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}

template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
    if(v.empty()) {
        cout << endl;
        return;
    }
    for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
    cout << v.back() << endl;
}

vector<int> gen_array(int n, int l, int r){
    int d = r-l;
    random_device rnd;
    mt19937 mt(rnd());
    vector<int> ans(n);
    int x = mt();
    for(int i = 0; i < n; i++) ans[i] = l+(mt()%d);
    return ans;
}

const int MX = 200000;
using P = pair<int, int>;

int e() { return 0; }

int add(int l, int r) { return l+r; }

int id() { return 0; }


int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n; cin >> n;
    vector<int> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    vector<int> v(MX+1);
    for(int i = 0; i <= MX; i++) v[i] = i;
    atcoder::lazy_segtree<int, add, e, int, add, add, id> sgt(v);
    priority_queue<P> que;
    que.push(P(MX, 0));
    int ans = 0;
    for(int i = 0; i < n; i++){
        int x = sgt.get(a[i]);
        if(x == 0) continue;
        ans++;
        vector<P> p;
        while(!que.empty() && que.top().first >= x+1){
            p.push_back(que.top());
            que.pop();
        }
        // debug_value(p.size());
        for(auto [len, l]: p){
            que.push(P(x, l));
            que.push(P(len-x, l+x));
            sgt.apply(l+x, l+len, -x);
        }
    }
    cout << ans << endl;
}