#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<climits>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<bitset>
#include<iomanip>
#include<functional>
using namespace std;

#define rep(i,j,n) for(int i=(j);i<(n);i++)
#define erep(i,j,n) for(int i=(j);i<=(n);i++)
#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(),i.rend()
#define INF 1e9
const int mod = 1e9+7;

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef pair<int, int> pi;
typedef long long i64;

vi v(3);

bool solve(int n) {
  int p = 0, m = 0;

  rep(i, 0, 3) {
    if(v[i] >= n) p += (v[i] - n) / 2;
    else m += n - v[i];
  }
  return (p >= m);
}

int binary_search() {
  int ok = INF;
  int ng = -1;

  while(abs(ok - ng) > 1) {
    int mid = (ok + ng) / 2;
    if(solve(mid)) ng = mid;
    else ok = mid;
  }
  return ng;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  rep(i, 0, 3) cin >> v[i];
  cout << binary_search() << endl;
}