#include <bits/stdc++.h>
using namespace std;
#define EMT ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const ll LINF = 2e18;
const double EPS = 1e-9;
signed main() { EMT
int n;
cin >> n;
vector<int> arr(n);
ll ans = 0;
for(int i = 0; i < n; i++)
cin >> arr[i];
int it = 0;
while(it < n) {
if(!arr[it]) {
it++;
continue;
}
int w = arr[it];
for(int i = it; i < n; i++) {
if(!arr[i])
break;
w = min(w, arr[i]);
}
ans++;
for(int i = it; i < n; i++) {
if(!arr[i])
break;
arr[i] -= w;
}
}
cout << ans << '\n';
}
