#include <bits/stdc++.h>

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

int main() {
    while (cin >> a[++n]);
    n--;
    for (int i = 1; i <= n; i++)res += a[i] * pow(2, n - 1);
    printf("%d", res);
    return 0;
}