func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   void read(T& x) {     cin >> x;   }   template <class H, class T>   void read(pair<H, T>& x) {     read(x.first);     read(x.second);   }   template <class A>   void read(vector<A>& v) {     for (auto& x : v) read(x);   }   template <class H, class... T>   void read(H& h, T&... t) {     read(h);     read(t...);   }   string to_string(const char* c) { return (string)c; }   string to_string(char c) { return (string)    + c; }   string to_string(string second) { return second; }   string to_string(bool b) { return b ?  True  :  False ; }   template <class A>   string to_string(vector<A> v) {     string second;     for (auto& x : v) second += to_string(x) +    ;     return second;   }   template <class H, class... T>   string to_string(H& h, T&... t) {     string second;     second += to_string(h);     second +=    ;     second += to_string(t...);     return second;   }   void print(string second) { cout << second <<   n ; }   template <class... A>   void print(A... a) {     print(to_string(a...));   }   int cdiv(int a, int b) { return a / b + !(a < 0 || a % b == 0); }   string tb(int x) {     string ans;     int c = x;     for (int i = log2(x); i >= 0; --i) {       if (pow(2, i) <= c) {         ans +=  1 ;         c -= pow(2, i);       } else {         ans +=  0 ;       }     }     return ans;   }   bool ispr(int x) {     if (x <= 1) {       return false;     }     for (int i = 2; i <= sqrt(x); ++i) {       if (x % i == 0) {         return false;       }     }     return true;   }   struct point {     int x;     int y;   };   const int MOD = 1e9 + 7;   const int MX = 2e5 + 5;   const long long INF = 1e18;   void solve() {     double n, k;     cin >> n >> k;     double dist = 0;     point prev;     read(prev.x, prev.y);     for (int i = 1; i < n; ++i) {       point now;       read(now.x, now.y);       dist += sqrt((now.x - prev.x) * (now.x - prev.x) +                    (now.y - prev.y) * (now.y - prev.y));       prev = now;     }     printf( %.9f , (dist * k) / 50);   }   int main() {     std::ios::sync_with_stdio(0);     std::cin.tie(0);     bool isT = 0;     if (isT) {       int t;       cin >> t;       while (t--) {         solve();       }       return 0;     }     solve();     return 0;   }   