#include<iostream> #include<algorithm> #include<functional> using namespace std; int main(){ int x; cin>>x; int s[x],t[x-3]; for(int i=0;i<x;++i) cin>>s[i]; for(int i=0;i<x-3;++i){ t[i]=s[i]+s[i+1]+s[i+2]; } sort(t,t+x-3); cout<<t[x-4]; return 0; }