#include <iostream>

using namespace std;

int main()
{
    int paketce_1, paketce_2;
    cin >> paketce_1 >> paketce_2;
    int zbir = 0;
    zbir = paketce_1 + paketce_2;
    zbir /= 2;
    zbir *= 7;
    cout << zbir << endl;
    return 0;
}