#include<iostream>
#include<algorithm>
using namespace std;
int main(void){
	int v[3];
	cin >> v[0] >> v[1] >> v[2];
	while (true){
		sort(v, v + 3);
		if (v[0] == v[2] || v[0] + 1 == v[2]) break;
		v[2] -= 2;
		v[0]++;
	}
	cout << v[0] << endl;
	return 0;
}