#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define loop(i,n) for(ll i=0;i<n;i++)
#define loopn(i,j,n) for(ll i=j;i<n;i++)
#define m_arr(arr, n) vector<ll>arr(n)
#define m_arre(arr) vector<ll>arr
#define m_set(sat) set<ll>sat
#define ppn(name) pair<ll,ll>name
#define pp pair<ll,ll>
#define sort_all(arr) sort(arr.begin(), arr.end())
#define pi 3.141592653589793238
//#define mod 1000000007

ll gcd(ll a, ll b){if(a==0)return b;if(b==0)return a;return gcd(b%a, a);}

ll power(ll a, ll b, ll mod)
{
    ll res=1;
    while(b>0)
    {
        if(b%2!=0)
            res = (res*1ll*a)%(mod*1ll*mod);
        b/=2;
        a=(a*1ll*a)%(mod*1ll*mod);
    }

    return res;
}


void solve()
{
    ll x, y, a, b;
    cin>>x>>y>>a>>b;

    if(x>a)
    {
        swap(x, a);
        swap(y, b);
    }

    double ans = (a*y + b*x)/double(y+b);
    cout<<fixed<<setprecision(9)<<ans<<endl;
    return;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    //int t;cin>>t;while(1)
    solve();
    return 0;
}

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

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

    long double X, Y, Z;
    cin >> X >> Y >> Z;
    long double iti = Y / X;
    for(int i = 1; i <= 10000000; i++){
        if(Z*iti <= (long double)(i)){
            cout << i-1 << '\n';
            exit(0);
        }
    }
    return 0;
}