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

using ll = long long;

vector<ll> rgb(3);

// x個のアクセサリー作れる？
bool ok(int x) {
    int a = 0, b = 0;
    for (int i = 0; i < 3; i++) {
        if (rgb[i] < x) a += (x - rgb[i]);
        else            b += (rgb[i] - x) / 2;
    }
    return b >= a;
}

int main() {
    cin >> rgb[0] >> rgb[1] >> rgb[2];
    ll left = -1;
    ll right = 10000001;
    while (right - left > 1) {
        int mid = (left + right) / 2;
        if (!ok(mid)) right = mid;
        else           left = mid;
    }
    cout << left << endl;

    return 0;
}