#include"bits/stdc++.h"

using namespace std;
#define REP(k,m,n) for(int (k)=(m);(k)<(n);(k)++)
#define rep(i,n) REP((i),0,(n))
using ll = long long;
using pll = pair<ll, ll>;
using tp3 = tuple<ll, ll, ll>;
constexpr int INF = 1 << 28;
constexpr ll INFL = 1ll << 60;
constexpr int dh[4] = { 0,1,0,-1 };
constexpr int dw[4] = { -1,0,1,0 };
bool isin(const int H, const int W, const int h, const int w) {
    return 0 <= h && h < H && 0 <= w && w < W;
}
// ============ template finished ============

int main()
{
    vector<double> v(3);
    rep(i, 3)cin >> v[i];
    auto opp = *min_element(v.begin(), v.end());
    auto all = accumulate(v.begin(), v.end(), 0.0);
    cout << fixed << setprecision(10) << (all - opp) / all << endl;
    return 0;
}