#include <fstream>

using namespace std;
ifstream cin("oo.in");
ofstream cout("oo.out");
const int dim = 1e5 + 1;
int v[ dim ], N;
int main()
{
    cin >> N;
    for ( int i = 0; i < N; ++i )
        cin >> v[ i ];
    v[ N ] = v[ 0 ];
    int maxim = 0;
    for ( int i = 1; i <= N; ++i )
    {
        maxim = max( maxim, v[ i ] + v[ i - 1 ] );
    }
    cout << maxim;
}