func_code_string: #include <bits/stdc++.h>   using namespace std;   const double sq = 1.73205080757;   int main() {     long long k, k1;     cin >> k;     k1 = k * 2;     k *= 2;     k1 -= k1 % 3;     k1++;     if (k1 > k) k1 -= 3;     long long h = 1, h1, an = 0;     while (k1 > 0) {       while (k1 * k1 + 3LL * h * h <= k * k &&              (k1 + 1) * (k1 + 1) + 3LL * (h - 1) * (h - 1) <= k * k)         h++;       h--;       if ((k1 - 1) % 6 == 0)         h1 = max(h - (h % 2 == 0), 0LL);       else         h1 = h - h % 2;       an += h1;       k1 -= 3;     }     cout << an * 2 - h1 << endl;   }   