#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) for(int i = (n) - 1; (i) >= 0; --i)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
#define MOD 1000007
#define INF 100000000
using namespace std;
typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PI;


int main() {
	int a[3];
	cin >> a[0] >> a[1] >> a[2];
	sort(a, a + 3);
	while (a[2] - a[0] > 2) {
		a[2] -= 2;
		a[0]++;
		sort(a, a + 3);
	}
	cout << a[0] << endl;
	return 0;
}