#include <bits/stdc++.h>
using namespace std;

#define FOR(i, k, l) for(int i = k; i < l; i++)
#define DFOR(i, k, l) for(int i = k; i > l; i--)
#define FA(i, k) for(int i = 0; i < int(k.size()); i++)
#define DFA(i, k) for(int i = int(k.size()) - 1; i > -1; i--)
#define ASKS(i) for(cin >> (i); (i)--;)

#define MAXINT 2147483647
#define endl '\n'
#define all(x) x.begin(), x.end()
#define fi first
#define se second

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef set<int> si;
typedef set<ll> sll;
typedef priority_queue<int> pqi;
typedef priority_queue<ll> pqll;
typedef priority_queue<int, vector<int>, greater<int>> pqig;
typedef priority_queue<ll, vector<ll>, greater<ll>> pqllg;

ld g(ld p, ld f, ld a, ld b){
    ld tf = sqrt(a * a + (1 - b) * (1 - b)) / f;
    ld tp = sqrt((1 - a) * (1 - a) + b * b) / p;
    return tp + tf;
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    freopen("forest.in", "r", stdin);
    freopen("forest.out", "w", stdout);
    cout << fixed << setprecision(12);

    ld p, f, a, l = 0, r = 1, m1, m2;
    cin >> p >> f >> a;
    while(r - l > 0.00000000000001){
        m1 = l + (r - l) / 3;
        m2 = r - (r - l) / 3;
        if(g(p, f, a, m1) > g(p, f, a, m2))
            l = m1;
        else
            r = m2;
    }
    cout << l;


    return 0;
}