Working on binary tree

I can't figure out how to construct it.
should 'p' and 'b' be closer or 'p' and 's'

The distance between the nodes is the distance between the values it represents. when things are in a binary tree, I don't really know how to keep them the same distance as the one from the paper.

looking at this link: http://ww4.aievolution.com/hbm1201/index.cfm?do=abs.viewAbs&abs=6470
It seems that there is a way of computing something called a "similiarity tree" from the similiarity matrix.

This study uses this paper: http://www.sciencedirect.com/science/article/pii/S0304397511007158
for constructing trees