func_code_string: #include <bits/stdc++.h>   using namespace std;   int f[100005], s[100005];   int main() {     int n, k, inp;     scanf( %d %d , &n, &k);     for (int i = 1; i < k + 1; i++) {       scanf( %d , &inp);       s[inp] = i;       if (!f[inp]) f[inp] = i;     }     int ans = 0;     for (int i = 1; i < n + 1; i++) {       if (!f[i]) {         ans += 3;         if (i == 1 || i == n) ans--;         continue;       }       int b = i - 1;       if (b >= 1 && s[b] < f[i]) ans++;       b = i + 1;       if (b <= n && s[b] < f[i]) ans++;     }     cout << ans <<   n ;     return 0;   }   