#include<stdio.h>
int main()
{
int t,n,a,b;
while(scanf("%d",&t)!=EOF)
while(t--)
scanf("%d",&n);
if(n>=1&&n<=30)
a=1;
for(b=1;b<=n;b++)
a=a*2;
}
a=a-1;
printf("%d\n",a);
return 0;