#include <bits/stdc++.h>
using namespace std;
int main() {
int n; cin >> n;
vector<int> a(n); for (auto& i : a) cin >> i;
int d = 0; for (int i = 1; i <= n; i++) d += abs(a[i % n] - a[i - 1]);
d = (d + 1) / 2;
int m = *max_element(a.begin(), a.end());
cout << max(m, d) << endl;
}
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