#include <bits/stdc++.h>

#ifdef local
#define safe std::cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#define debug(args...) qqbx(#args, args)
#define orange(args...) danb(#args, args)
using std::cerr;
template <typename ...T> void qqbx(const char *s, T ...args) {
  int cnt = sizeof...(T);
  ((cerr << "\e[1;32m(" << s << ") = ("), ..., (cerr << args << (--cnt ? ", " : ")\e[0m\n")));
}
template <typename I> void danb(const char *s, I L, I R) {
  cerr << "\e[1;32m[ " << s << " ] = [ ";
  for (int f = 0; L != R; ++L) cerr << (f++ ? ", " : "") << *L;
  cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) ((void)0)
#define orange(...) ((void)0)
#endif // local
#define all(v) begin(v),end(v)

using namespace std;
using llf = long double;

signed main() {
  cin.tie(nullptr) -> sync_with_stdio(false);
  llf d, s, e;
  cin >> d >> s >> e;

  // d - e - s
  llf x = min(d - e - s, s);

  llf A = s / d * ((s - x) / s);
  llf B = (1 - s / d) * x / (d - e - s);

  cout << fixed << setprecision(20);
  // llf P = s / d * (d - s);
  // llf Q = (1 - s / d) * (d - s - e);
  // debug(A, B);
  // debug(P, Q);
  // llf ans = (A * P + B * Q) / (P + Q);
  // debug(ans);
  cout << A + B << '\n';
}