#include <iostream>
using namespace std;
 
int main(){
	int R, G, B;
	cin >> R >> G >> B;
 
	int lo = 0, hi = 10000100;
	while(hi - lo > 1){
		int mid = (hi + lo) / 2;
 
		int need = 0, change = 0;
		if(R < mid)need += mid - R; else change += (R - mid) / 2;
		if(G < mid)need += mid - G; else change += (G - mid) / 2;
		if(B < mid)need += mid - B; else change += (B - mid) / 2;
 
		if(need <= change){
			lo = mid;
		} else {
			hi = mid;
		}
	}
 
	cout << lo << endl;
	return 0;
}