There are $n$ rings placed onto $10$ rods labeled from '0' to '9'. You are given a string rings of length $2 \cdot n$ that describes the rings placed on the rods.

The string rings is formatted in $2$ character pairs such that:
The character at rings[$2 \cdot i$] describes the color of the $i$-th ring, which is either 'R' (red), 'G' (green), or 'B' (blue).
The character at rings[$2 \cdot i + 1$] describes the rod label where the $i$-th ring is placed, which is between '0' and '9'.

Return the total number of rods that have all $3$ colors of rings placed on them.

Constraints:

• rings.length $== 2 \cdot n$

• $1 \leq n \leq 100$

• rings[i] where i is even is either 'R', 'G', or 'B' ($0$ indexed).

• rings[i] where i is odd is a digit from '0' to '9' ($0$ indexed).

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.