func_code_string: #include <bits/stdc++.h>   using namespace std;   double res, a, b;   int main() {     int n, k;     cin >> n >> k;     vector<double> x(n), y(n);     for (int i = 0; i < n; i++) {       cin >> x[i] >> y[i];       if (i) {         a = x[i] - x[i - 1];         b = y[i] - y[i - 1];         res += sqrt((a * a) + (b * b));       }     }     res /= 50;     cout << setprecision(10) << res * k << endl;   }   