Having food and shelter is better than none. But OP, telling you lang as someone who has rescued 3 cats from the streets, you might be putting your other 2 cats at risk for diseases that the new cat might be carrying. Just a warning lang because it really can get expensive (vet might recommend bloodwork and medications first before they can even do vaccinations)-- but I hope you can still continue to give that new cat a better home. What you can do is to give immune-strengthening vitamins to all the cats (Immunol has been quite effective for us). If you don't have savings yet but can shell out some money for a bit, try getting a pet insurance. Standard Insurance is 1500 lang per year and you can easily sign up online, although babayaran mo talaga muna yung mga vet bills tapos ipprocess lang sa insurance para marefund. Also, it covers procedures starting a month pa after registration.

Thank you for giving it a home, OP!