var n, i: Longint;
       a: array[0..1000] of Longint;

begin
 readln(n);
 a[0] := 0;
 for i := 1 to n do
  read(a[i]);
 for i := 2 to n do
  if (a[i - 2] > a[i - 1])
   then a[i] := a[i] + a[i - 2]
   else a[i] := a[i] + a[i - 1];
 writeln(a[n]);
end.
