#include <bits/stdc++.h>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;

bool ok(int a, int b) {
  if(a == b) return 1;
  if(a+1 == b) return 1;
  return 0;
}

int main() {
  
  ll v[3];
  ll mn = 1<<29;
  rep(i, 3) cin >> v[i], mn = min(mn, v[i]);
  
  ll ans = mn;
  rep(i, 3) { v[i] -= mn; }
  while(1) {
    sort(v, v+3);
    v[2] -= 2; v[0] ++;
    if(v[2] <= 0) break;
    
    mn = 1<<29;
    rep(i, 3) mn = min(mn, v[i]);
    rep(i, 3) v[i] -= mn;
    ans += mn;
  }
  
  cout << ans << endl;
  
  return 0;
}