func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     cin >> n >> k;     vector<int> questions(k);     vector<int> previsited(n + 1, 0);     vector<int> posvisited(n + 1, 0);     vector<int> vis;     int tot_non = n;     for (int i = 0; i < k; i++) {       cin >> questions[i];       if (!previsited[questions[i]]) {         tot_non--;         vis.push_back(questions[i]);         previsited[questions[i]] = i + 1;       }       posvisited[questions[i]] = i + 1;     }     int ans = tot_non * 3;     if (previsited[1] == 0) ans--;     if (previsited[n] == 0) ans--;     for (int i = 0; i < vis.size(); i++) {       if (vis[i] <= n - 1 && previsited[vis[i]] > posvisited[vis[i] + 1]) {         ans++;       }       if (vis[i] >= 2 && previsited[vis[i]] > posvisited[vis[i] - 1]) {         ans++;       }     }     cout << ans << endl;   }   