#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> RGB;

bool solve(int x) {
	bool flag = false;
	int need = 0, amari = 0;
	for (int i = 0; i < 3; i++) {
		if (RGB[i] < x)need += (x - RGB[i]);
		else amari += (RGB[i] - x) / 2;
	}

	return amari >= need;
}

int main()
{
	RGB.resize(3);
	cin >> RGB[0] >> RGB[1] >> RGB[2];

	long long left = -1;
	long long right = 10000001;
	int mid;
	while (left < right) {
		mid = (left + right) / 2;
		if (!solve(mid)) {
			right = mid;
		}
		else {
			left = mid + 1;
		}
	}

	cout << left-1 << endl;

    return 0;
}