#include <iostream>
using namespace std;
int main() {
int n;
cin >> n;
int A[n];
int suma = 0;
int wynik = 0;
for (int i = 0; i < n; i++){
cin >> A[i];
}
for (int i = 1; i < n - 1; i++){
suma = A[i - 1] + A[i] + A[i + 1];
if (suma > wynik){
wynik = suma;
}
}
cout << wynik;
return 0;
}
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