#include using namespace std; using ll = long long; constexpr double ticks_per_sec = 2800000000; constexpr double ticks_per_sec_inv = 1.0 / ticks_per_sec; inline double rdtsc() { // in seconds uint32_t lo, hi; asm volatile ("rdtsc" : "=a" (lo), "=d" (hi)); return (((uint64_t)hi << 32) | lo) * ticks_per_sec_inv; } constexpr double TLE = 2; // sec int main() { double clock_begin = rdtsc(); cin.tie(0); ios::sync_with_stdio(false); int n; cin >> n; long double p, q; cin >> p >> q; q += p; int seed = 0; mt19937 mt(seed); uniform_real_distribution rnd(0, 1); ll cnt = 0; double clock_end = clock_begin + TLE * 0.85; ll loop_cnt = 0; const int MAX_TRY = 200000; while (rdtsc() < clock_end) { loop_cnt++; int cur = 1; int d = 1; for (int i = 0; i < MAX_TRY; i++) { long double val = rnd(mt); if (val <= p) { d = -d; cur += d; } else if (val <= q) { cur += d; } else { break; } if (cur == n + 1) break; if (cur == 0) { cnt++; break; } } } cout << fixed << setprecision(15) << (double)cnt / loop_cnt << endl; return 0; }