program sec;

var row,srow:string;
    i,bl,br,variables:byte;
    c:char;
    error,bx,bp,si,di:boolean;
    letters:array['a'..'z'] of byte;
begin

while not eof do
begin
readln(row);

error := false;

for i:=1 to length(row) do
  if not((pos(row[i],'+-[]BDIPSX')>0)
   or (row[i] in ['a'..'z'])
    or (row[i] in ['0'..'9']))
     then error := true;

for c:='a' to 'z' do letters[c]:=0;
for i:=1 to length(row) do if row[i] in ['a'..'z'] then inc(letters[row[i]]);
variables:=0;
for c:='a' to 'z' do if letters[c]>0 then inc(variables);
if variables>1 then error:=true;


if (pos('bx',row)>0) or (pos('bX',row)>0) or (pos('Bx',row)>0) or (pos('BX',row)>0)
 then bx:=true
 else bx:=false;

if (pos('bp',row)>0) or (pos('bP',row)>0) or (pos('Bp',row)>0) or (pos('BP',row)>0)
 then bp:=true
 else bp:=false;

if (pos('si',row)>0) or (pos('sI',row)>0) or (pos('Si',row)>0) or (pos('SI',row)>0)
 then si:=true
 else si:=false;

if (pos('di',row)>0) or (pos('dI',row)>0) or (pos('Di',row)>0) or (pos('dI',row)>0)
 then di:=true
 else di:=false;

if (bx and bp) or (si and di) then error := true;

if (row[1] = '-') or (row[length(row)] = '-') or
   (row[1] = '+') or (row[length(row)] = '+')
     then error := true;
bl := 0;
br := 0;
for i:=1 to length(row) do
 begin
 if row[i] = '[' then inc(bl);
 if row[i] = ']' then inc(br);
 end;

if not error then if br<>bl then error := true;

if not error then
 for i:=2 to length(row)-1 do
   begin
   if row[i] = '-' then if (row[i+1] = ']') or (row[i-1] = '[')
     then error := true;
   if row[i] = '+' then if (row[i+1] = ']') or (row[i-1] = '[')
     then error := true;
   end;

if error then writeln('ERROR')
         else writeln('OK');
end;

end.