include <bits/stdc++.h> using namespace std; #define int long long (54686)#define vi vector<int> #define pi acos(-1) double ebs = 1e-6; double getM1(double s) { return sqrt(s * 4 * pi); } double getM2(double s, int x) { return sqrt(s * x * 4 * tan(pi / x)); } void solve() { int n, len; cin >> n >> len; vi a(n); for (int i = 0; i < n; i++) { cin >> a[i]; } auto check = [&](double x) { double sum = 0; for (int i = 0; i < n; i++) { if (a[i] == -1) { sum += getM1(x); } else { sum += getM2(x, a[i]); } } return sum <= len; }; double l = 0, r = len / 4.0 / pi * len; while (r - l >= ebs) { double m = (l + r) / 2; if (check(m)) l = m; else r = m; } cout << l << '\n'; } signed main() { ios::sync_with_stdio(false); cin.tie(nullptr); solve(); } // S1 = x * (n / x)^2 / 4tan(2pi / x / 2) = n * n / x / 4tan(pi / x) // n^2 = S1 * x * 4tan(pi / x) // S2 = (n / 2pi)^2 * pi = n * n / 4pi // n^2 = S2 * 4pi