func_code_string: #include <bits/stdc++.h>   using namespace std;   float r, p, m;   float a[100 * 1000];   int main() {     cin >> m >> r;     p = r * sqrt(2);     a[0] = 2 * r;     a[1] = 2 * r + p;     for (int i = (2), _end = (m); i < _end; ++i) {       a[i] = 2 * p;       a[i] += 2 * r * (i - 1);     }     float sum = 0;     sum += a[0] * m;     for (int i = (1), _end = (m); i < _end; ++i) {       sum += 2 * (m - i) * a[i];     }     sum = sum / (m * m);     printf( %.9f n , sum);     return 0;   }   