#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <cstdio>
using namespace std;
int n;
double A, e, m, l, r;
vector <double> h;
int bin(double m){
h[1] = m;
for (int i = 2; i < n; i++)
{
h[i] = 2 * h[i - 1] + 2 - h[i - 2];
if (h[i] <= 0) return 0;
}
return 1;
}
int main()
{
// ios_base::sync_with_stdio(false);
freopen("garland.in", "r", stdin);
freopen("garland.out", "w", stdout);
cin >> n >> A;
h.resize(n);
h[0] = A;
l = 0;
r = A;
e = 0.0000001;
while (l + e < r)
{
m = (l + r) / 2;
if (bin(m)){
r = m;
}
else{
l = m;
}
}
printf("%.2f", h[n - 1]);
return 0;
}
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