#include <bits/stdc++.h>   using namespace std;   const long double e = 1e-2;   int k;   long double R, r, l;   long double x, y, xl, yl, xr, yr;   long double a, b, c, S;   long double COS[12], SIN[12];   bool check(long double x, long double y) {     long double s = 0;     for (int i = 0; i < 12; i += 2)       s = max(s, ((x + COS[i]) * (x + COS[i])) + ((y + SIN[i]) * (y + SIN[i])));     return s <= l + r;   }   bool end(long double x, long double y) {     long double s = 1e+60;     for (int i = 0; i < 12; i += 2)       s = min(s, ((x + COS[i]) * (x + COS[i])) + ((y + SIN[i]) * (y + SIN[i])));     return s > S;   }   int main() {     R = 1;     r = sqrt(((R) * (R)) - ((0.5) * (0.5)));     for (int i = 0; i < 12; i++) {       COS[i] = cos(((i * 30) * M_PI / 180));       SIN[i] = sin(((i * 30) * M_PI / 180));     }     scanf( %d , &k);     l = k;     l *= l;     S = k + 3;     S *= S;     x = (k + 2) / 3 * 3 * COS[2];     y = (k + 2) / 3 * 3 * SIN[2];     xl = xr = x;     yl = yr = y;     long long ans = 0;     do {       long double s;       s = y * xr - x * yr;       while (s > 0 && abs(s) > e && !check(xr, yr)) {         xr += 2 * r * COS[5];         yr += 2 * r * SIN[5];         s = y * xr - x * yr;       }       while (check(xr, yr)) {         xr -= 2 * r * COS[5];         yr -= 2 * r * SIN[5];       }       s = y * xl - x * yl;       while (s < 0 && abs(s) > e && !check(xl, yl)) {         xl += 2 * r * COS[11];         yl += 2 * r * SIN[11];         s = y * xl - x * yl;       }       while (check(xl, yl)) {         xl -= 2 * r * COS[11];         yl -= 2 * r * SIN[11];       }       long double L = sqrt(((xl - xr) * (xl - xr)) + ((yl - yr) * (yl - yr)));       ans += max((long long)((L + r) / (2 * r)) - 1, 0LL);       xl += 2 * r * COS[7];       yl += 2 * r * SIN[7];       xr += 2 * r * COS[9];       yr += 2 * r * SIN[9];     } while (!end(xr, yr) || !end(xl, yl));     cout << ans << endl;     return 0;   }   