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
