How to properly feed stray cats?
1. Try to put out food at night when there are fewer pedestrians to avoid being seen by people who don't like stray cats and causing conflict. Also, the garbage collectors have already gone off duty and won't take away the food you put out.
2. Try to feed them dry cat food, as wet food attracts mosquitoes and flies, which may cause complaints from nearby residents.
3. Place the grain in a concealed place as much as possible to prevent it from being thrown away by those with ill intentions. 
4. When feeding stray cats, avoid close contact such as petting or hugging them. This will prevent stray cats from losing their wariness of people and reduce the risk of human-caused harm.
5. Feed them only until they are 70% full, allowing stray cats to retain their ability to find food on their own.
6. If someone sees you feeding stray cats and then confronts you, please do not engage in conflict. The best approach is to communicate politely, explaining that the stray cats are unattended and hungry, and that it is pitiful for them. Just as it is difficult for someone to be hungry all day, so too is this approach.
7. Regarding water placement, use disposable cylindrical containers to hold the water and place them in concealed locations, such as in short bushes within the community, where people cannot see them but cats can find them. Placing them in obvious locations risks people adding poison to the water. I have once seen someone spray insecticide into the water I placed there.
The baby food available in supermarkets isn't very good. I don't know what price range you're willing to pay (I'm assuming you're still a student). You could consider buying online. More expensive options include Meow Mix from the US, or Gold Shot from Japan, while cheaper options include domestic brands like Good Master and Zhenbao. You could also consider rinsing leftover fish, shrimp, and meat from the cafeteria and mixing it with rice to feed the baby. However, homemade food like this can easily develop an unpleasant odor, which might be off-putting.
Finally, thank you so much on behalf of all the cats and dogs! Just to add, there's no need to deliberately buy separate cat foods, as the ingredients are generally very similar. My dachshund, who has eaten cat food for over ten years, is much healthier than my other two who have been eating the same food for years. So, feeding your cats and dogs with cat food is sufficient. For stray cats and dogs, cat food isn't the most important thing; the key is that they are well-fed and watered, and that their food is safe. You can put the cat's feeding area in a high place so that the cat doesn't go hungry and the dog doesn't overeat.
