All Tracks Data Structures Arrays 1-D Problem

In a parallel universe, there are not just two charges like positive and negative, but there are $$26$$ charges represented by  $$lower$$ english alphabets.

Charges have a property of killing each other or in other words neutralizing each other if they are of same charge and next to each other.

You are given a string $$s$$ where each $$s_i$$ represents a charge, where $$0 \le i \le |s|-1 $$.

You need to output $$size$$ of final string followed by string after which no neutralizing is possible.