Hi @Motoi_Tokimatsu ,
I went in search of the original Advent of Code question that was posed, and found it here. This will hopefully be useful to anybody wishing to understand what the challenge is.
It is an interesting question, and in the past I have used java snippet to break cells down into individual characters, which is one of the issues you face. I even wrote a component that did just that when I first started with KNIME
However, your question is how to achieve it without java snippet, so that rules out my component 
Take a look at this… hopefully the annotations explain sufficiently…
Workflow attached here for download
AoC2020Day6-takbb.knwf (1.3 MB)