Represents first and last numbers of each type ( modulo 0 and 1 )
L = [ 0 for i in range ( 2 ) ] NEW_LINE R = [ 0 for i in range ( 2 ) ] NEW_LINE L [ l % 2 ] = l NEW_LINE R [ r % 2 ] = r NEW_LINE l += 1 NEW_LINE r -= 1 NEW_LINE if ( l <= tR and r >= tL ) : NEW_LINE INDENT L [ l % 2 ] , R [ r % 2 ] = l , r NEW_LINE DEDENT