#include<iostream>
#include<cmath>
using namespace std;
long long ans, n = -1, t;
int main()
{
    while (cin >> t)
    {
        ans += t, n++;
    }
    cout << ans * (long long)pow(2, n);
    return 0;
}

pow默认返回double，记得强转long long，不然三个WA