#include <bits/stdc++.h>
using namespace std;
#define repl(i, l, r) for (ll i = (l); i < (r); i++)
#define rep(i, n) repl(i, 0, n)
#define CST(x) cout << fixed << setprecision(x)
using ll = long long;
const ll MOD = 1000000007;
const int inf = 1e9 + 10;
const ll INF = 4e18 + 10;
const int dx[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
const int dy[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0};
int main() {
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(false);

	double a[3];
	rep(i, 3) cin >> a[i];
	double p = a[0] + a[1] + a[2];
	double ans = 0;
	rep(i, 3) {
		rep(j, 2) {
			if (j == 0) {
				ans = max(ans, a[i] / p);
			} else {
				double now = 0;
				rep(k, 3) {
					if (k != i) now += a[k];
				}
				now /= p;
				ans = max(ans, now);
			}
		}
	}
	CST(10) << ans << endl;

	return 0;
}