Add task 23 (opener)
Add task 23 (opener)

nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms,nesterione/problem-solving-and-algorithms