const
  lim=100000;
var
  a,s:array[1..lim] of longint;
  i,j,n,t,sol:longint;
begin
  assign(input,'oo.in');
  reset(input);
  readln(n);
  for i:=1 to n do read(s[i]);
  close(input);
  a[1]:=0;
  a[2]:=0;
  a[3]:=s[2]+s[3];
  for i:=4 to n do
  begin
    a[i]:=s[i]+s[i-1]+a[i-3];
    if a[i-1]>a[i] then a[i]:=a[i-1];
  end;
  sol:=a[n];
  a[1]:=0;
  a[2]:=s[1]+s[2];
  a[3]:=s[3]+s[2];
  for i:=4 to n-1 do
  begin
    a[i]:=s[i]+s[i-1] + a[i-3];
    if a[i-1]>a[i] then a[i]:=a[i-1];
  end;
  if a[n-1]>sol then sol:=a[n-1];
  assign(output,'oo.out');
  rewrite(output);
  writeln(sol);
  close(output);
end.