machine learning – Decision Tree from a Dataset

First, I'm not sure the question fits this site. Otherwise, let me know and I propose it.

In my current class (AI), we study decision trees. One of my exercises is to build a tree from a simple raw data set. I am able to extract the first decision node based on the given dataset, but I do not know how to build the remaining nodes because none of the remaining attributes has a precise answer in the given data set. All the indicators that put me on the right path are very appreciated!

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I could say that A1 is the first node of my tree since all the lines point to y = 1 when A1 is 1