#include <bits/stdc++.h>
#define ll long long
#define ld long double
using namespace std;

const int N = 2e5 + 5, mod = 998244353;


// (d - e)
// 1 /

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);


    ld d, s, e;
    cin >> d >> s >> e;
    cout << fixed << setprecision(10);
    if(2 * s + e <= d) {
        // d - e -> s / d;
        ld rem = d - e - s;
        ld z = (e / d) * (1 / rem);
        cout << s * (1 / d + z);
    }
    else {
        ld rem = d - e - s;
        ld taken = s - rem;
        ld z = (e / d) * (1 / rem);
        cout << s / d + rem * z;
    }

    return 0;
}