#include <iostream>
#include <string>
#include <fstream>
#include<algorithm>

using namespace std;

const long double MIN = 0.0000000000, MAX = 1e9;
int n, m;
int a[1000], b[1000];

bool func(long double x) {
    for (int i = 0; i < n; i++) {
        x -= (long double) (x + m) / a[i];
        if (x <= 0.0)
            return false;
        x -= (long double) (x + m) / b[i];
    }

    return true;
}

int main() {
    cin >> n;
    cin >> m;

    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    for (int i = 0; i < n; i++) {
        cin >> b[i];
    }

    long double l = MIN, r = MAX;

    while (r - l > 1) {
        long double m = (r + l) / 2;
        if (func(m))
            r = m;
        else
            l = m;
    }

    cout << r;

    /*system("pause");*/

    return 0;
}