#include <iostream>
#include <cmath>

using namespace std;

double sumSequence (int n, int quantity, double s) {
    s += pow(-1, n)/((n*n + 2)*(n-1));
    if (n < quantity) return sumSequence(n+1, quantity, s);
    else return s;
}

int main() {
    int quantity;
    double accuracy, ans;
    cin >> quantity >> accuracy;
    ans = sumSequence(2, quantity, 0);
    if (ans < accuracy) cout << "None";
    else cout << ans;
    return 0;
}