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

int main() {
	long long R, G, B, Left = -1, Right = 10000001;
	cin >> R >> G >> B;
	while (Right - Left > 1) {
		long long MID = (Left + Right) / 2;
		long long UP = 0, DOWN = 0;
		if (MID <= R) UP += (R - MID) / 2;
		else DOWN += MID - R;
		if (MID <= G) UP += (G - MID) / 2;
		else DOWN += MID - G;
		if (MID <= B) UP += (B - MID) / 2;
		else DOWN += MID - B;
		if (UP >= DOWN) Left = MID;
		else Right = MID;
	}
	cout << Left << endl;
}