func_code_string: #include <bits/stdc++.h>   using namespace std;   long long pow(long long a, long long b) {     if (b == 0) {       return 1;     }     if (b % 2 == 0) {       return pow((a % 1000000007) * (a % 1000000007), b / 2) % 1000000007;     } else {       return (a % 1000000007) *              (pow((a % 1000000007) * (a % 1000000007), (b - 1) / 2) % 1000000007);     }   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     int i, j, k, n;     cin >> n >> k;     double x[n], y[n];     for (i = 0; i < n; i++) {       cin >> x[i] >> y[i];     }     double ans = 0.000000000;     for (i = 1; i < n; i++) {       ans += sqrt((x[i] - x[i - 1]) * (x[i] - x[i - 1]) +                   (y[i] - y[i - 1]) * (y[i] - y[i - 1]));     }     double f = (ans * double(k)) / (50.0000000000);     cout << fixed << setprecision(10) << f <<   n ;   }   