#include <bits/stdc++.h> using namespace std; long long n, a[2] = {0, 9}, b[2] = {0, 1}; int main() { cin >> n; for (long long i = 2; i <= n; i++) { a[i % 2] = b[(i - 1) % 2] + 9 * a[(i - 1) % 2]; b[i % 2] = a[(i - 1) % 2] + 9 * b[(i - 1) % 2]; } cout << a[n % 2] - a[(n - 1) % 2] << endl; return 0; }