func_code_string: #include <bits/stdc++.h>   using namespace std;   int main(int argc, char *argv[]) {     double m, R, res[100005], tmp = 0;     cin >> m >> R;     res[0] = 2;     res[1] = 2 + sqrt(2);     for (int i = 2; i <= 100000; i++) res[i] = 2 * (i - 1) + 2 * sqrt(2);     tmp += m * res[0];     if (m == 1)       printf( %.9lf , R * tmp);     else {       for (int i = 1; i <= m - 1; i++) {         tmp += 2 * (m - i) * res[i];       }       printf( %.9lf n , R * tmp / (m * m));     }     return EXIT_SUCCESS;   }   