#include<bits/stdc++.h>
using namespace std;
int a;
int main(){
/*
freopen (".in","r",stdin);
freopen (".out","w",stdout);
*/
int k=0,cnt=0;
while(scanf("%d",&a)!=EOF){
	cnt+=a;
	k++;
} 
long long sum=cnt*int(pow(2,k-1));
cout<<sum;






/*
fclose(stdin);
fclose(stdout);
*/
	return 0;
}