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Problems

Number of N-digit numbers containing the digit 7

Number of N-digit numbers containing the digit 7

Find K - number of N-digit natural numbers, which contain in their records at least one digit 7.

Input

The only positive integerN (1N10).

Output

The desired numberK.

Time limit 1 second
Memory limit 64 MiB
Input example #1
2
Output example #1
18