Hi. I’m a student and wanted to explore more about machine learning. I am trying to make a neural network model that classify child-adult. My process is by first  detecting their body then their head/face to get the ratio of the head over body. What I’m confused about is how many dataset should I make. Like do I have to make a separate dataset for head? body? or child? adult? I hope someone can help me with this problem. Thank you in advance and have a great day.