Broken window phenomenon means that if the window of a house is broken, no one will repair it. Soon, other windows will be broken inexplicably. Therefore, if the bad phenomenon in the environment is allowed to exist, it will induce people to follow suit or even intensify.
According to the above definition, which of the following is not a broken window phenomenon?
Some graffiti appeared on one wall and was not removed. Soon, the wall was full of messy and ugly things.