#include // clang-format off using Int = long long; #define REP_(i, a_, b_, a, b, ...) for (Int i = (a), lim##i = (b); i < lim##i; i++) #define REP(i, ...) REP_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__) struct SetupIO { SetupIO() { std::cin.tie(nullptr), std::ios::sync_with_stdio(false), std::cout << std::fixed << std::setprecision(13); } } setup_io; #ifndef dump #define dump(...) #endif // clang-format on /** * author: knshnb * created: Fri Jun 12 21:20:41 JST 2020 **/ signed main() { double p; std::cin >> p; std::cout << (1 / (1 - p)) - 1 << std::endl; }