Is it ok if I try marijuana once?

I know marijuana and alcohol are brain damaging drugs, but I would like to try just one time to see how it is like. I've been high on alcohol three times and I've felt really good but sad after a while. I've read that addiction to alcohol and marijuana are almost the same, and I can control myself from drinking alcohol so I think I could just try it once and don't try it again. Is something bad going to happen if I try it, such an important neuron loss or damage in my nervous system?