func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1000005;   int v[N], c[N];   int n, k;   vector<int> z;   void input() {     scanf( %d %d , &n, &k);     for (int i = 1; i <= n; i++) scanf( %d , &v[i]);     for (int i = 1; i <= n; i++) scanf( %d , &c[i]);     z.push_back(min(100 * v[n], c[n]));     for (int i = n - 1; i >= 1; i--) {       int larger = max(z.back(), v[i] * 100);       int smaller = min(larger, c[i]);       z.push_back(min(larger, smaller));     }   }   void pro() {     sort(z.begin(), z.end());     double ans = 0;     double chance = 1;     for (int i = 0; i < k; i++) {       ans += z[i] * chance * k / (n - i);       chance *= 1. * (n - k - i) / (n - i);     }     cout << fixed << setprecision(10) << ans << endl;   }   int main() {     input();     pro();   }   