#include <bits/stdc++.h>
using namespace std;
int main()
{
int a;
cin>>a;
vector<int>ss(a);
for(auto &i:ss){
cin>>i;
}
for(int i=2;i<a;i++){
if(ss[i-1]>ss[i-2]){
ss[i]=ss[i]+ss[i-2];
}
else{
ss[i]=ss[i]+ss[i-1];
}
}
cout<<ss[a-1];
return 0;
}
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