#include<bits/stdc++.h>

using namespace std;
typedef long long LL;
const int N = 110;
LL a[N];
int n;
LL res;

int main() {
    //录入进来，终止条件是CTRL+D
    while (cin >> a[++n]);
    n--;
    for (int i = 1; i <= n; i++)
        res += a[i] * pow(2, n - 1);
    cout << res << endl;
    return 0;
}