{$A+,B-,D+,E+,F-,G-,I+,L+,N-,O-,P-,Q-,R-,S+,T-,V+,X+}
{$M 16384,0,655360}

program CHAIN;

 var
   f: text;
   N, i, count, _one: integer;
   k: longint;

begin
 _one:=0;
 Assign (f, 'CHAIN.DAT');
 Reset (f);
 Readln (f, N);
 for i:=1 to N do
  begin
    Read (f, k);
    if k=1 then inc (_one);
  end;
 Close (f);
 i:=0;
 if N>(_one*2) then i:=1;
 count:=N-_one-i;
 Assign (f, 'CHAIN.RES');
 Rewrite (f);
 Writeln (f, count);
 Close (f);
end.