Understanding the evolution of a set of genes or species is a fundamental problem in evolutionary biology. In this talk, we are given a set of phylogenetic trees that describe conflicting evolutionary histories for a set of species, and our task is to find a single tree that agrees with the input trees as much as possible. We study a few variants of this problem, where disagreement between two trees is measured by the number of leaves that need to be deleted before the trees are identical. At the end of the talk, we'll briefly discuss how the situation becomes more complex when phylogenetic trees and generalised to phylogenetic networks.