#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr int N = 1e6+5;
int n;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
int mx = 0;
vector<queue<int>> v(5005);
for(int i = 0; i < n; i++) {
int x;
cin >> x;
v[x].push(i);
mx = max(mx, x);
}
int c = 0;
for(int i = mx; i >= 1; i--) {
if(v[i].empty()) continue;
c++;
int now = i;
int pos = -1;
while(!v[now].empty()) {
if(pos < v[now].front()) {
pos = v[now].front();
v[now].pop();
now--;
}
else {
break;
}
}
}
cout << c << "\n";
return 0;
}
