Here is a coding problem:
<PROBLEM>

Here is an attempted solution:
<SOLUTION>

Rate the difficulty of the programming problem on a scale from 1 to 10 based on the problem description and the attempted solution. 1 indicates the probelm is very easy to solve, while 10 indicates the problem is very hard to solve.
Note that the attempted solution might be incorrect.
Rate the difficulty of the programming problem on a scale from 1 to 10. Just respond immediately with the number.
