Problems
Number of N-digit numbers containing the digit 7
Number of N-digit numbers containing the digit 7
Find \textbf{K} - number of \textbf{N}-digit natural numbers, which contain in their records at least one digit \textbf{7}.
\InputFile
The only positive integer \textbf{N} (\textbf{1} ≤ \textbf{N} ≤ \textbf{10}).
\OutputFile
The desired number \textbf{K}.
Input example #1
2
Output example #1
18