#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

int main(){
    int x,y,z;
    cin>>x>>y>>z;
    int d=abs(x-y);
    if(d<=z)cout<<max(x,y)+(z-d)/2<<endl;
    else cout<<min(x,y)+z<<endl;
}