#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 7;
set<int> s[N];
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
for (int i = 1; i <= n; ++i) {
int x;
cin >> x;
s[x].insert(i);
}
int ans = 0;
for (int i = N - 1; i >= 0; --i) {
for (auto pos : s[i]) {
int h = i - 1;
int last = pos;
ans++;
auto it = s[h].lower_bound(pos);
while (it != s[h].end()) {
last = *it;
s[h].erase(it);
h--;
it = s[h].lower_bound(last);
}
}
}
cout << ans << "\n";
return 0;
}
