Anthracene, C₁₄H₁₀, is a tricyclic aromatic compound that consists of three six-membered rings fused with each other along the edges. The Lewis structure of anthracene is shown below:

It is expected that all of the bonds, despite the resonance, will not be equivalent in terms of their bond lengths. How many C-C bonds are expected to be greater in bond length than the other C-C bonds?