Insert first n catalan elements to set
s . add ( a ) ; NEW_LINE if ( n >= 2 ) : NEW_LINE INDENT s . add ( b ) ; NEW_LINE DEDENT for i in range ( 2 , n ) : NEW_LINE INDENT s . add ( catalan [ i ] ) ; NEW_LINE DEDENT temp = set ( ) NEW_LINE for i in range ( n ) : NEW_LINE