I struggle with autism and I don't have the energy or will to continue with my life. What are the deadliest pills that you can buy?

What are the most deadly pills at a pharmacy that you don't need a prescription for?

You don't have to agree with my choice, I understand there are mixed feelings around self-termination, but I feel that my life is only an uphill battle and there isn't any reason for me to exist in the first place, so I think I should have the right to choose to die on my own terms and hope you'll respect my right to make this choice even if you disagree. I'm not looking for my mind to be changed, I just need to know what I should buy for this to finally end