func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long int n, k;     cin >> n >> k;     vector<pair<long double, long double>> v;     for (long long int i = 0; i < n; i++) {       long double x, y;       cin >> x >> y;       v.push_back(make_pair(x, y));     }     long double sum = 0;     for (long long int i = 1; i < v.size(); i++) {       long double x1 = v[i - 1].first, y1 = v[i - 1].second, x2 = v[i].first,                   y2 = v[i].second;       long double dis = sqrt(((x2 - x1) * (x2 - x1)) + ((y2 - y1) * (y2 - y1)));       sum = sum + dis;     }     long double ans = ((1.0 / 50.0) * sum) * k;     printf( %0.9Lf n , ans);   }   