#include<bits/stdc++.h>

using namespace std;

int main()
{
    int l,r,a;
    cin >> l >> r >> a;

    int difference = abs(l-r);
    int mini = min(l,r);
    if(difference>=a)
    {

        cout << (mini+difference)*2 << endl;
    }
    else
    {
        //int maxi = max(l,r);
        int rest = a-difference;
        rest /= 2;
        cout << (maxi+rest)*2 << endl;

    }

    return 0;
}