Two numbers can be fused by putting one in front of the other to make the largest number possible.

For example, \(29\) and \(71\) can be fused to form \(7129\).

A list of numbers can be fused by repeatedly fusing pairs of numbers of the same length to form the biggest number possible.

For example, given the sequence \(1\ 3\ 4\ 2\), the \(1\) and \(3\) are fused to give \(31\) and the \(4\) and \(2\) are fused to give \(42\).

Then the \(31\) and \(42\) are fused to give \(4231\).

If the original sequence is

\(\begin{array}{c}
4&5&3&6&7&2&9&4&5&6&4&7&8&2&1&5 \\
\end{array}\)

what is the last digit of the final fused number?