南城以南青如衫北城以北白如雪
[nán chéng yĭ nán qīng rú shān bĕi chéng yĭ bĕi bái rú xuĕ]
'South of the southern city blue/green as shirt north of northern city white as snow'. It creates an image of two places separated by contrasts in color (and temperature) to reflect contrasting emotions or experiences of life, evoking nostalgia and bittersweet memory.