#include <stdio.h>
#include <math.h>
int l = 0;
long long s[30] = {0}, sum = 0;
char ss[30] = {0};
int main()
{
    for (int i = 0; i < 30; i += 1)
    {
        scanf("%lld%c", &s[i], &ss[i]);
        sum += s[i];
        l += 1;
        if (ss[i] == '\n')
            break;
    }
    sum = (long long)(sum * pow(2, l - 1));
    printf("%lld", sum);
    return 0;
}