func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n;   inline bool check2(long long x, long long y3) {     return (x * x + y3 * y3 * 3 <= n * n);   }   inline bool check(long long x, long long y3) {     return check2(x - 2, y3) & check2(x - 1, y3 - 1) & check2(x + 1, y3 - 1) &            check2(x + 2, y3) & check2(x + 1, y3 + 1) & check2(x - 1, y3 + 1);   }   long long calc(long long x, long long d) {     long long l = 0, r = 3e6;     while (l < r) {       long long mid = (l + r + 1) / 2;       long long y3 = d + mid * 2;       if (check(x, y3))         l = mid;       else         r = mid - 1;     }     long long ret = r * 2;     if (d == 0 && check(x, 0)) ret += 1;     if (d == 1 && check(x, d)) ret += 2;     return ret;   }   int main() {     ios::sync_with_stdio(false);     cin >> n;     n *= 2;     long long s = 0;     int x = 3, d = 1;     while (true) {       long long t = calc(x, d);       if (t == 0) break;       s += t;       x += 3, d ^= 1;     }     s *= 2;     s += calc(0, 0);     cout << s << endl;   }   