#include<iostream> using namespace std; int main(){ int i,n,a,b,c,ms=0; cin>>n>>a>>b>>c; ms=a+b+c; for(i=4;i<=n;i++){ a=b; b=c; cin>>c; if(a+b+c>ms) ms=a+b+c; } cout<<ms; return 0; }