program name;
var
   i,n:integer;
   a,s,d:longint;
begin
     read(n);
     for i:=1 to n do
         begin
              read(a);
              s:=s+a;
              if (a=1) or (a=0) then s:=s-1;
              d:=s-n;
         end;
     write(d);
end.