How does this poem "Arriving in Lin 'an" describe the partiality in the Southern Song Dynasty?

Lin 'an House is a four-line poem by Lin Sheng, a poet in the Song Dynasty. The first sentence of this poem points out the characteristics of Lin 'an City, with green hills and terraced fields, and the second sentence points out the endless singing and dancing by the West Lake in a rhetorical tone. The last two sentences describe the indulgence of the rulers in sarcastic language, and through the comparison between "Hangzhou" and "Bianzhou", the decadent essence of "refugees" is revealed, and the author's anger at the failure of the rulers to recover lost land and his concern about the fate of the country are also shown. The whole poem is ingenious in conception, accurate in wording and cynical, and is written from a lively scene; Extremely indignant, but not abusive: it is indeed a masterpiece in allegorical poetry.