#include<iostream>
using namespace std;
int n,a[21],ans=2.1e9,sum1;
void dfs(int k,int sum1){
	if(k<=n)
		dfs(k+1,sum1+a[k]),dfs(k+1,sum1);
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	dfs(n,0);
	printf("%d",sum1);
	return 0;
}
				I2luY2x1ZGU8aW9zdHJlYW0+CnVzaW5nIG5hbWVzcGFjZSBzdGQ7CmludCBuLGFbMjFdLGFucz0yLjFlOSxzdW0xOwp2b2lkIGRmcyhpbnQgayxpbnQgc3VtMSl7CglpZihrPD1uKQoJCWRmcyhrKzEsc3VtMSthW2tdKSxkZnMoaysxLHN1bTEpOwp9CmludCBtYWluKCl7CglzY2FuZigiJWQiLCZuKTsKCWZvcihpbnQgaT0xO2k8PW47aSsrKQoJCXNjYW5mKCIlZCIsJmFbaV0pOwoJZGZzKG4sMCk7CglwcmludGYoIiVkIixzdW0xKTsKCXJldHVybiAwOwp9