func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[300010];   int main() {     int n;     cin >> n;     for (int i = 1; i <= n; ++i) {       scanf( %d , &a[i]);     }     long long ans = 0;     vector<int> v;     for (int i = 1; i <= n; ++i) {       ans += a[i] / 2;       if (a[i] % 2 != 0) {         v.push_back(i);       }     }     stack<int> q;     if (v.size() == 0) {       cout << ans << endl;       return 0;     }     q.push(v[0]);     for (int i = 1; i < v.size(); ++i) {       if (q.size() && (v[i] - q.top()) % 2 != 0) {         q.pop();         ans++;         continue;       }       q.push(v[i]);     }     cout << ans << endl;     return 0;   }   