#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr int N = 1e6+5;
int n, a[N], nxt[N];
bool vis[N];
int find_next(int x) {
if(!vis[nxt[x]]) return nxt[x];
return nxt[x] = find_next(nxt[x]);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
priority_queue<pair<int,int>> pq;
for(int i = 0; i < n; i++) {
cin >> a[i];
nxt[i] = i + 1;
pq.push(make_pair(a[i], i));
}
int c = 0;
while(!pq.empty()) {
int pos = pq.top().second;
pq.pop();
if(vis[pos]) {
continue;
}
int cur = a[pos];
int now = pos;
while(now != n) {
if(a[now] == cur) {
cur--;
vis[now] = 1;
}
now = find_next(now);
}
c++;
}
cout << c;
return 0;
}
