func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, k, x1, y1, x2, y2;     long double s = 0;     scanf( %d %d , &n, &k);     scanf( %d %d , &x1, &y1);     for (int i = 1; i < n; i++) {       scanf( %d %d , &x2, &y2);       s += (long double)sqrt((long double)(x2 - x1) * (x2 - x1) +                              (long double)(y2 - y1) * (y2 - y1));       x1 = x2;       y1 = y2;     }     printf( %.6Lf , s * (long double)k / (long double)50);     return 0;   }   