#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const ll LongINF=1e13+7;
const int INF=1e9+7;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};

template<class T> inline bool chmin(T& a, T b) {if (a > b) {a = b;return true;}return false;}
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b;return true;}return false;}
template <class T, class Y>T GCD(T a, Y b){if(a<b){int c=a;a=b;b=c;}if (a % b == 0){return b;}return GCD(b, a % b);}
void clear(queue<pair<int, int>> &q){queue<pair<int, int>> empty;swap(q, empty);} //queueの中身の型は適時変更を忘れない

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

int main(){
    int X,Y,Z;
    cin>>X>>Y>>Z;
    int ANS=0;
    int MAX=max(X,Y);
    int Dif=abs(X-Y);
    ANS+=MAX-Dif;
    if(Z<Dif){
        ANS+=Z;
    }else{
        ANS+=Dif;
        Z-=Dif;
        if(Z%2==0)Z/=2;
        else Z=(Z-1)/2;
        ANS+=Z;
    }
    cout<<ANS<<endl;
    return 0;
}

//a=97,z=122