#include <bits/stdc++.h> using namespace std; int main() { ios::sync_with_stdio(false); cin.tie(0); int n; if (!(cin >> n)) return 0; vector<int> raw(n); for (int i = 0; i < n; i++) cin >> raw[i]; // 1. Remove consecutive duplicates vector<int> h; h.push_back(0); // Boundary for (int i = 0; i < n; i++) { if (h.empty() || raw[i] != h.back()) { h.push_back(raw[i]); } } h.push_back(0); // Boundary // 2. Identify local extrema and their impact // We use a map to store the net change in island count at each altitude map<int, int> changes; for (int i = 1; i < h.size() - 1; i++) { if (h[i-1] < h[i] && h[i+1] < h[i]) { // Peak: At sea level h[i], an island disappears changes[h[i]]--; } else if (h[i-1] > h[i] && h[i+1] > h[i]) { // Valley: At sea level h[i], an island splits (new island created) changes[h[i]]++; } } // 3. Sweep through altitudes from highest to lowest int max_islands = 0; int current_islands = 0; // We process from high altitude to low altitude. // If we start with sea level very high, islands = 0. // As sea level drops below a peak, current_islands++ // As sea level drops below a valley, current_islands-- for (auto it = changes.rbegin(); it != changes.rend(); ++it) { // Note: The logic in the loop is inverted because we are going // from top to bottom. A peak encountered from the top increases islands. current_islands -= it->second; max_islands = max(max_islands, current_islands); } // If all altitudes were 0, the answer is 0. Otherwise, at least 1. if (h.size() <= 2) cout << 0 << endl; else cout << max(1, max_islands) << endl; return 0; }