#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

// #define int long long

#define pii pair<int, int>
#define pll pair<ld, ld>
#define vi vector<int>
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define mp make_pair
#define pb push_back
#define sz(v) (int)(v).size()
// #define endl '\n'

const ld eps = 1e-8;
const ll mod = 1e9 + 7;
const int inf0 = 1e9 + 10;
const ll inf = 2e18 + 10;

void solve();

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
#ifdef LC
    freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
#endif
    cout << fixed << setprecision(20);
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}

const int N = 2e5;

void solve() {
    int a, b, c;
    cin >> a >> b >> c;
    c /= 2;
    if (c == 0) {
        cout << 2 * a << "\n";
    }
    else {
        cout << 2 * (a + b) + 3 * c << "\n";    
    }
}

// g++ -DLC -o a a.cpp && ./a