}
			}
			score := int64(le) * int64(len(cc)-le)
			if score > bestScore {
				bestScore = score
				bestIdx = idx
				bestByte = b
			}
		}
	}

	// The split must be at least 1:n-1 because we have at least 2 distinct strings; they
	// have to be different somewhere.
	// TODO: what if the best split is still pretty bad?
	if bestScore == 0 {
		base.Fatalf("unable to split string set")
	}