#include <iostream>
using namespace std;
int main()
{
int i, n, a, max1, max2, i1, i2;
cin>>n;
for(i=1; i<=n; i++)
{
cin>>a;
if(a>max1)
{
max1=a;
i1=i;
}
if(a>max2 && a!=max1)
{
max2=a;
i2=i;
}
}
int k=1;
while(k*2<=(i2-i1))
k=k*2;
while(k*2<=(i1-i2))
k=k*2;
cout<<max1+max2-k;
}