#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>


int main() {
  int x, y, z;
  cin >> x >> y >> z;
  if (x+z <= y) cout << x+z << endl;
  else if (y+z <= x) cout << y+z << endl;
  else cout << (x+y+z)/2 << endl;

  
}