#include using namespace std; int main(void) { int H, A, D; cin >> H >> A >> D; double ans = 1e9; for (int i = 0; i <= (H + A - 1) / A; i++) { ans = min(ans, i + 1.5 * (max(0, (H - i * A + D - 1)) / D)); } printf("%.10f\n", ans); return 0; }