#include <iostream>
#include <algorithm>

using namespace std;

int main() {
	int c[3];
	cin >> c[0] >> c[1] >> c[2];
	for (;;) {
		sort(c, c + 3);
		if (c[0] == c[2] || c[0] + 1 == c[2]) {
			break;
		}
		c[2] -= 2;
		c[0] += 1;
	}
	cout << c[0] << endl;
	return 0;
}