func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int N, M;     cin >> N >> M;     vector<int> ceff(N * 2);     for (int i = 0; i < N; ++i) {       cin >> ceff[i * 2];     }     cin >> ceff[N * 2 - 1];     for (int i = 1; i < N; ++i) {       cin >> ceff[i * 2 - 1];     }     double cur = M;     for (int i = N * 2 - 1; i >= 0; --i) {       if (ceff[i] == 1) {         cout << -1 << endl;         return 0;       }       cur = cur / (ceff[i] - 1) + cur;     }     cout << setprecision(10) << fixed;     cout << cur - M << endl;     return 0;   }   